Make Script.prototype.nameOrSourceURL use indexOf search first before trying to match with a RegExp.

src/messages.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 477 matching lines @@
  * @return {?string} script name if present, value for //@ sourceURL comment
  * otherwise.
  */
 Script.prototype.nameOrSourceURL = function() {
   if (this.name)
     return this.name;
   // TODO(608): the spaces in a regexp below had to be escaped as \040
   // because this file is being processed by js2c whose handling of spaces
   // in regexps is broken. Also, ['"] are excluded from allowed URLs to
   // avoid matches against sources that invoke evals with sourceURL.
-  var sourceUrlPattern =
-    /\/\/@[\040\t]sourceURL=[\040\t]*([^\s'"]*)[\040\t]*$/m;
-  var match = sourceUrlPattern.exec(this.source);
-  return match ? match[1] : this.name;
+  // A better solution would be to detect these special comments in
+  // the scanner/parser.
+  var source = ToString(this.source);
+  var sourceUrlPos = %StringIndexOf(source, "sourceURL=", 0);
+  if (sourceUrlPos > 4) {
+    var sourceUrlPattern =
+        /\/\/@[\040\t]sourceURL=[\040\t]*([^\s\'\"]*)[\040\t]*$/gm;
+    // Don't reuse lastMatchInfo here, so we create a new array with room
+    // for four captures (array with length one longer than the index
+    // of the fourth capture, where the numbering is zero-based).
+    var matchInfo = new InternalArray(CAPTURE(3) + 1);
+    var match =
+        %_RegExpExec(sourceUrlPattern, source, sourceUrlPos - 4, matchInfo);
+    if (match) {
+      return SubString(source, matchInfo[CAPTURE(2)], matchInfo[CAPTURE(3)]);
+    }
+  }
+  return this.name;
 }
 
 
 /**
  * Class for source location. A source location is a position within some
  * source with the following properties:
  *   script   : script object for the source
  *   line     : source line number
  *   column   : source column within the line
  *   position : position within the source
@@ skipping 554 matching lines @@
     else throw e;
   }
 }
 
 
 InstallFunctions($Error.prototype, DONT_ENUM, ['toString', errorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);