Unify settings of _scriptName and scriptDirectory. NFC

This move the code for setting these into a single place and avoids
duplication.

Automatic rebaseline of codesize expectations. NFC

This is an automatic change generated by tools/maint/rebaseline_tests.py.

The following (71) test expectation files were updated by
running the tests with `--rebaseline`:

```
browser/test_small_js_flags.js.size: 4380 => 4371 [-9 bytes / -0.21%]
other/codesize/test_codesize_cxx_ctors1.gzsize: 8352 => 8361 [+9 bytes / +0.11%]
other/codesize/test_codesize_cxx_ctors2.gzsize: 8336 => 8346 [+10 bytes / +0.12%]
other/codesize/test_codesize_cxx_except.gzsize: 9358 => 9369 [+11 bytes / +0.12%]
other/codesize/test_codesize_cxx_except_wasm.gzsize: 8321 => 8325 [+4 bytes / +0.05%]
other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize: 8321 => 8325 [+4 bytes / +0.05%]
other/codesize/test_codesize_cxx_lto.gzsize: 8348 => 8356 [+8 bytes / +0.10%]
other/codesize/test_codesize_cxx_mangle.gzsize: 9361 => 9370 [+9 bytes / +0.10%]
other/codesize/test_codesize_cxx_noexcept.gzsize: 8352 => 8361 [+9 bytes / +0.11%]
other/codesize/test_codesize_cxx_wasmfs.gzsize: 3653 => 3656 [+3 bytes / +0.08%]
other/codesize/test_codesize_cxx_wasmfs.jssize: 7914 => 7913 [-1 bytes / -0.01%]
other/codesize/test_codesize_files_js_fs.gzsize: 7656 => 7659 [+3 bytes / +0.04%]
other/codesize/test_codesize_files_wasmfs.gzsize: 2882 => 2884 [+2 bytes / +0.07%]
other/codesize/test_codesize_files_wasmfs.jssize: 6202 => 6200 [-2 bytes / -0.03%]
other/codesize/test_codesize_hello_O0.gzsize: 8017 => 8014 [-3 bytes / -0.04%]
other/codesize/test_codesize_hello_O0.jssize: 21597 => 21589 [-8 bytes / -0.04%]
other/codesize/test_codesize_hello_O1.gzsize: 2697 => 2692 [-5 bytes / -0.19%]
other/codesize/test_codesize_hello_O1.jssize: 6911 => 6906 [-5 bytes / -0.07%]
other/codesize/test_codesize_hello_O2.gzsize: 2359 => 2361 [+2 bytes / +0.08%]
other/codesize/test_codesize_hello_O2.jssize: 4835 => 4833 [-2 bytes / -0.04%]
other/codesize/test_codesize_hello_O3.gzsize: 2298 => 2304 [+6 bytes / +0.26%]
other/codesize/test_codesize_hello_O3.jssize: 4757 => 4755 [-2 bytes / -0.04%]
other/codesize/test_codesize_hello_Os.gzsize: 2298 => 2304 [+6 bytes / +0.26%]
other/codesize/test_codesize_hello_Os.jssize: 4757 => 4755 [-2 bytes / -0.04%]
other/codesize/test_codesize_hello_Oz.gzsize: 2281 => 2284 [+3 bytes / +0.13%]
other/codesize/test_codesize_hello_Oz.jssize: 4724 => 4722 [-2 bytes / -0.04%]
other/codesize/test_codesize_hello_dylink.gzsize: 6023 => 6021 [-2 bytes / -0.03%]
other/codesize/test_codesize_hello_dylink.jssize: 13300 => 13296 [-4 bytes / -0.03%]
other/codesize/test_codesize_hello_export_nothing.gzsize: 1682 => 1686 [+4 bytes / +0.24%]
other/codesize/test_codesize_hello_export_nothing.jssize: 3637 => 3632 [-5 bytes / -0.14%]
other/codesize/test_codesize_hello_wasmfs.gzsize: 2298 => 2304 [+6 bytes / +0.26%]
other/codesize/test_codesize_hello_wasmfs.jssize: 4757 => 4755 [-2 bytes / -0.04%]
other/codesize/test_codesize_libcxxabi_message_O3.gzsize: 1876 => 1880 [+4 bytes / +0.21%]
other/codesize/test_codesize_libcxxabi_message_O3.jssize: 4000 => 3996 [-4 bytes / -0.10%]
other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize: 1914 => 1915 [+1 bytes / +0.05%]
other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize: 4048 => 4044 [-4 bytes / -0.10%]
other/codesize/test_codesize_mem_O3.gzsize: 2328 => 2329 [+1 bytes / +0.04%]
other/codesize/test_codesize_mem_O3.jssize: 4892 => 4890 [-2 bytes / -0.04%]
other/codesize/test_codesize_mem_O3_grow.gzsize: 2478 => 2480 [+2 bytes / +0.08%]
other/codesize/test_codesize_mem_O3_grow.jssize: 5177 => 5175 [-2 bytes / -0.04%]
other/codesize/test_codesize_mem_O3_grow_standalone.gzsize: 2180 => 2184 [+4 bytes / +0.18%]
other/codesize/test_codesize_mem_O3_grow_standalone.jssize: 4585 => 4583 [-2 bytes / -0.04%]
other/codesize/test_codesize_mem_O3_standalone.gzsize: 2143 => 2149 [+6 bytes / +0.28%]
other/codesize/test_codesize_mem_O3_standalone.jssize: 4517 => 4513 [-4 bytes / -0.09%]
other/codesize/test_codesize_mem_O3_standalone_lib.gzsize: 1900 => 1903 [+3 bytes / +0.16%]
other/codesize/test_codesize_mem_O3_standalone_lib.jssize: 4047 => 4043 [-4 bytes / -0.10%]
other/codesize/test_codesize_mem_O3_standalone_narg.gzsize: 1914 => 1915 [+1 bytes / +0.05%]
other/codesize/test_codesize_mem_O3_standalone_narg.jssize: 4048 => 4044 [-4 bytes / -0.10%]
other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize: 1914 => 1915 [+1 bytes / +0.05%]
other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize: 4048 => 4044 [-4 bytes / -0.10%]
other/codesize/test_codesize_minimal_64.gzsize: 1439 => 1442 [+3 bytes / +0.21%]
other/codesize/test_codesize_minimal_64.jssize: 3064 => 3058 [-6 bytes / -0.20%]
other/codesize/test_codesize_minimal_O0.gzsize: 6554 => 6549 [-5 bytes / -0.08%]
other/codesize/test_codesize_minimal_O0.jssize: 17637 => 17629 [-8 bytes / -0.05%]
other/codesize/test_codesize_minimal_O1.gzsize: 1531 => 1532 [+1 bytes / +0.07%]
other/codesize/test_codesize_minimal_O1.jssize: 3713 => 3706 [-7 bytes / -0.19%]
other/codesize/test_codesize_minimal_O2.gzsize: 1380 => 1381 [+1 bytes / +0.07%]
other/codesize/test_codesize_minimal_O2.jssize: 2812 => 2806 [-6 bytes / -0.21%]
other/codesize/test_codesize_minimal_O3.jssize: 2762 => 2756 [-6 bytes / -0.22%]
other/codesize/test_codesize_minimal_Os.jssize: 2762 => 2756 [-6 bytes / -0.22%]
other/codesize/test_codesize_minimal_Oz-ctors.jssize: 2747 => 2741 [-6 bytes / -0.22%]
other/codesize/test_codesize_minimal_Oz.jssize: 2762 => 2756 [-6 bytes / -0.22%]
other/codesize/test_codesize_minimal_esm.gzsize: 1496 => 1411 [-85 bytes / -5.68%]
other/codesize/test_codesize_minimal_esm.jssize: 3138 => 2929 [-209 bytes / -6.66%]
other/codesize/test_codesize_minimal_pthreads.gzsize: 4184 => 4157 [-27 bytes / -0.65%]
other/codesize/test_codesize_minimal_pthreads.jssize: 8711 => 8593 [-118 bytes / -1.35%]
other/codesize/test_codesize_minimal_wasmfs.jssize: 2762 => 2756 [-6 bytes / -0.22%]
other/test_INCOMING_MODULE_JS_API.js.size: 3772 => 3913 [+141 bytes / +3.74%]
other/test_unoptimized_code_size.js.size: 53866 => 53867 [+1 bytes / +0.00%]
other/test_unoptimized_code_size_no_asserts.js.size: 29065 => 29067 [+2 bytes / +0.01%]
other/test_unoptimized_code_size_strict.js.size: 52649 => 52650 [+1 bytes / +0.00%]

Average change: -0.15% (-6.66% - +3.74%)
```

src/shell.js

@@ -139,9 +139,9 @@ var quit_ = (status, toThrow) => {
   throw toThrow;
 };
 
-#if SHARED_MEMORY && !MODULARIZE
-// In MODULARIZE mode _scriptName needs to be captured already at the very top of the page immediately when the page is parsed, so it is generated there
-// before the page load. In non-MODULARIZE modes generate it here.
+#if !MODULARIZE
+// In MODULARIZE mode, _scriptName is captured already in the outer scope
+// In non-MODULARIZE mode, we simply calculate it here.
 var _scriptName = (typeof document != 'undefined') ? document.currentScript?.src : undefined;
 
 #if ENVIRONMENT_MAY_BE_NODE
@@ -156,10 +156,26 @@ if (ENVIRONMENT_IS_NODE) {
 if (ENVIRONMENT_IS_WORKER) {
   _scriptName = self.location.href;
 }
-#endif // SHARED_MEMORY && !MODULARIZE
+#endif // MODULARIZE
 
 // `/` should be present at the end if `scriptDirectory` is not empty
 var scriptDirectory = '';
+#if ENVIRONMENT_MAY_BE_WEB || ENVIRONMENT_MAY_BE_WORKER
+// blob urls look like blob:http://site.com/etc/etc and we cannot infer anything from them.
+// otherwise, slice off the final part of the url to find the script directory.
+// if scriptDirectory does not contain a slash, lastIndexOf will return -1,
+// and scriptDirectory will correctly be replaced with an empty string.
+// If scriptDirectory contains a query (starting with ?) or a fragment (starting with #),
+// they are removed because they could contain a slash.
+if (_scriptName && !_scriptName.startsWith('blob:')) {
+  scriptDirectory = _scriptName.substr(0, _scriptName.replace(/[?#].*/, '').lastIndexOf('/')+1);
+}
+#else
+if (_scriptName) {
+  scriptDirectory = _scriptName.substr(0, _scriptName.lastIndexOf('/')+1);
+}
+#endif
+
 function locateFile(path) {
 #if RUNTIME_DEBUG
   dbg('locateFile:', path, 'scriptDirectory:', scriptDirectory);
@@ -191,22 +207,14 @@ if (ENVIRONMENT_IS_NODE) {
   }
 #endif
 
+  // These modules will usually be used on Node.js. Load them eagerly to avoid
+  // the complexity of lazy-loading.
 #if EXPORT_ES6
   var fs = await import('fs');
   var nodePath = await import('path');
-  var url = await import('url');
-  // EXPORT_ES6 + ENVIRONMENT_IS_NODE always requires use of import.meta.url,
-  // since there's no way getting the current absolute path of the module when
-  // support for that is not available.
-  if (!import.meta.url.startsWith('data:')) {
-    scriptDirectory = nodePath.dirname(url.fileURLToPath(import.meta.url)) + '/';
-  }
 #else
-  // These modules will usually be used on Node.js. Load them eagerly to avoid
-  // the complexity of lazy-loading.
   var fs = require('fs');
   var nodePath = require('path');
-  scriptDirectory = __dirname + '/';
 #endif
 
 #include "node_shell_read.js"
@@ -338,30 +346,6 @@ if (ENVIRONMENT_IS_SHELL) {
 // ENVIRONMENT_IS_NODE.
 #if ENVIRONMENT_MAY_BE_WEB || ENVIRONMENT_MAY_BE_WORKER
 if (ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) {
-  if (ENVIRONMENT_IS_WORKER) { // Check worker, not web, since window could be polyfilled
-    scriptDirectory = self.location.href;
-  } else if (typeof document != 'undefined' && document.currentScript) { // web
-    scriptDirectory = document.currentScript.src;
-  }
-#if MODULARIZE
-  // When MODULARIZE, this JS may be executed later, after document.currentScript
-  // is gone, so we saved it, and we use it here instead of any other info.
-  if (_scriptName) {
-    scriptDirectory = _scriptName;
-  }
-#endif
-  // blob urls look like blob:http://site.com/etc/etc and we cannot infer anything from them.
-  // otherwise, slice off the final part of the url to find the script directory.
-  // if scriptDirectory does not contain a slash, lastIndexOf will return -1,
-  // and scriptDirectory will correctly be replaced with an empty string.
-  // If scriptDirectory contains a query (starting with ?) or a fragment (starting with #),
-  // they are removed because they could contain a slash.
-  if (scriptDirectory.startsWith('blob:')) {
-    scriptDirectory = '';
-  } else {
-    scriptDirectory = scriptDirectory.substr(0, scriptDirectory.replace(/[?#].*/, '').lastIndexOf('/')+1);
-  }
-
 #if ENVIRONMENT && ASSERTIONS
   if (!(typeof window == 'object' || typeof WorkerGlobalScope != 'undefined')) throw new Error('not compiled for this environment (did you build to HTML and try to run it not on the web, or set ENVIRONMENT to something - like node - and run it someplace else - like on the web?)');
 #endif

test/browser/test_small_js_flags.js.size

@@ -1 +1 @@
-4380
+4371

test/other/codesize/test_codesize_cxx_ctors1.gzsize

@@ -1 +1 @@
-8352
+8361

test/other/codesize/test_codesize_cxx_ctors2.gzsize

@@ -1 +1 @@
-8336
+8346

test/other/codesize/test_codesize_cxx_except.gzsize

@@ -1 +1 @@
-9358
+9369

test/other/codesize/test_codesize_cxx_except_wasm.gzsize

@@ -1 +1 @@
-8321
+8325

test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize

@@ -1 +1 @@
-8321
+8325

test/other/codesize/test_codesize_cxx_lto.gzsize

@@ -1 +1 @@
-8348
+8356

test/other/codesize/test_codesize_cxx_mangle.gzsize

@@ -1 +1 @@
-9361
+9370

test/other/codesize/test_codesize_cxx_noexcept.gzsize

@@ -1 +1 @@
-8352
+8361

test/other/codesize/test_codesize_cxx_wasmfs.gzsize

@@ -1 +1 @@
-3653
+3656

test/other/codesize/test_codesize_cxx_wasmfs.jssize

@@ -1 +1 @@
-7914
+7913

test/other/codesize/test_codesize_files_js_fs.gzsize

@@ -1 +1 @@
-7656
+7659

test/other/codesize/test_codesize_files_wasmfs.gzsize

@@ -1 +1 @@
-2882
+2884

test/other/codesize/test_codesize_files_wasmfs.jssize

@@ -1 +1 @@
-6202
+6200

test/other/codesize/test_codesize_hello_O0.gzsize

@@ -1 +1 @@
-8017
+8014

test/other/codesize/test_codesize_hello_O0.jssize

@@ -1 +1 @@
-21597
+21589

test/other/codesize/test_codesize_hello_O1.gzsize

@@ -1 +1 @@
-2697
+2692

test/other/codesize/test_codesize_hello_O1.jssize

@@ -1 +1 @@
-6911
+6906

test/other/codesize/test_codesize_hello_O2.gzsize

@@ -1 +1 @@
-2359
+2361

test/other/codesize/test_codesize_hello_O2.jssize

@@ -1 +1 @@
-4835
+4833

test/other/codesize/test_codesize_hello_O3.gzsize

@@ -1 +1 @@
-2298
+2304

test/other/codesize/test_codesize_hello_O3.jssize

@@ -1 +1 @@
-4757
+4755

test/other/codesize/test_codesize_hello_Os.gzsize

@@ -1 +1 @@
-2298
+2304

test/other/codesize/test_codesize_hello_Os.jssize

@@ -1 +1 @@
-4757
+4755

test/other/codesize/test_codesize_hello_Oz.gzsize

@@ -1 +1 @@
-2281
+2284

test/other/codesize/test_codesize_hello_Oz.jssize

@@ -1 +1 @@
-4724
+4722

test/other/codesize/test_codesize_hello_dylink.gzsize

@@ -1 +1 @@
-6023
+6021

test/other/codesize/test_codesize_hello_dylink.jssize

@@ -1 +1 @@
-13300
+13296

test/other/codesize/test_codesize_hello_export_nothing.gzsize

@@ -1 +1 @@
-1682
+1686

test/other/codesize/test_codesize_hello_export_nothing.jssize

@@ -1 +1 @@
-3637
+3632

test/other/codesize/test_codesize_hello_wasmfs.gzsize

@@ -1 +1 @@
-2298
+2304

test/other/codesize/test_codesize_hello_wasmfs.jssize

@@ -1 +1 @@
-4757
+4755

test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize

@@ -1 +1 @@
-1876
+1880

test/other/codesize/test_codesize_libcxxabi_message_O3.jssize

@@ -1 +1 @@
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+3996

test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize

@@ -1 +1 @@
-1914
+1915

test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize

@@ -1 +1 @@
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+4044

test/other/codesize/test_codesize_mem_O3.gzsize

@@ -1 +1 @@
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+2329

test/other/codesize/test_codesize_mem_O3.jssize

@@ -1 +1 @@
-4892
+4890

test/other/codesize/test_codesize_mem_O3_grow.gzsize

@@ -1 +1 @@
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+2480

test/other/codesize/test_codesize_mem_O3_grow.jssize

@@ -1 +1 @@
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+5175

test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize

@@ -1 +1 @@
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+2184

test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize

@@ -1 +1 @@
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+4583

test/other/codesize/test_codesize_mem_O3_standalone.gzsize

@@ -1 +1 @@
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+2149

test/other/codesize/test_codesize_mem_O3_standalone.jssize

@@ -1 +1 @@
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+4513

test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize

@@ -1 +1 @@
-1900
+1903

test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize

@@ -1 +1 @@
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+4043

test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize

@@ -1 +1 @@
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+1915

test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize

@@ -1 +1 @@
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test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize

@@ -1 +1 @@
-1914
+1915

test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize

@@ -1 +1 @@
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+4044

test/other/codesize/test_codesize_minimal_64.gzsize

@@ -1 +1 @@
-1439
+1442

test/other/codesize/test_codesize_minimal_64.jssize

@@ -1 +1 @@
-3064
+3058

test/other/codesize/test_codesize_minimal_O0.gzsize

@@ -1 +1 @@
-6554
+6549

test/other/codesize/test_codesize_minimal_O0.jssize

@@ -1 +1 @@
-17637
+17629

test/other/codesize/test_codesize_minimal_O1.gzsize

@@ -1 +1 @@
-1531
+1532

test/other/codesize/test_codesize_minimal_O1.jssize

@@ -1 +1 @@
-3713
+3706

test/other/codesize/test_codesize_minimal_O2.gzsize

@@ -1 +1 @@
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+1381

test/other/codesize/test_codesize_minimal_O2.jssize

@@ -1 +1 @@
-2812
+2806

test/other/codesize/test_codesize_minimal_O3.jssize

@@ -1 +1 @@
-2762
+2756

test/other/codesize/test_codesize_minimal_Os.jssize

@@ -1 +1 @@
-2762
+2756

test/other/codesize/test_codesize_minimal_Oz-ctors.jssize

@@ -1 +1 @@
-2747
+2741

test/other/codesize/test_codesize_minimal_Oz.jssize

@@ -1 +1 @@
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test/other/codesize/test_codesize_minimal_esm.gzsize

@@ -1 +1 @@
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test/other/codesize/test_codesize_minimal_esm.jssize

@@ -1 +1 @@
-3138
+2929

test/other/codesize/test_codesize_minimal_pthreads.gzsize

@@ -1 +1 @@
-4184
+4157

test/other/codesize/test_codesize_minimal_pthreads.jssize

@@ -1 +1 @@
-8711
+8593

test/other/codesize/test_codesize_minimal_wasmfs.jssize

@@ -1 +1 @@
-2762
+2756

test/other/test_INCOMING_MODULE_JS_API.js.size

@@ -1 +1 @@
-3772
+3913

test/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-53866
+53867

test/other/test_unoptimized_code_size_no_asserts.js.size

@@ -1 +1 @@
-29065
+29067

test/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-52649
+52650