Support extracting source mapping url defined by //@ sourceMappingURL=<url> comment.

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index de388214c7dffeec6b4ae71e353e29184ccb46cc..4fd7c4b411e252a7aaa19cfbcd57bec73511fd84 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -497,6 +497,26 @@ Script.prototype.lineCount = function() {
 Script.prototype.nameOrSourceURL = function() {
   if (this.name)
     return this.name;
+  return this.findMagicComment("sourceURL");
+}
+
+
+/**
+ * Returns script source mapping url, if present.
+ *
+ * @return {?string} script source mapping url, if present.
+ */
+Script.prototype.sourceMappingURL = function() {
+  return this.findMagicComment("sourceMappingURL");
+}
+
+
+/**
+ * Returns the value of the magic comment "//@ name=<value>", if present.
+ *
+ * @return {?string} the value of the magic comment, if present.
+ */
+Script.prototype.findMagicComment = function(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
@@ -504,21 +524,20 @@ Script.prototype.nameOrSourceURL = function() {
   // 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]*$/gm;
+  var position = %StringIndexOf(source, name + "=", 0);
+  if (position > 4) {
+    var pattern = "\/\/@[ \t]" + name + "=[\040\t]*([^\\s\'\"]*)[\040\t]*$";
+    var regexp = new $RegExp(pattern, "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);
+        %_RegExpExec(regexp, source, position - 4, matchInfo);
     if (match) {
       return SubString(source, matchInfo[CAPTURE(2)], matchInfo[CAPTURE(3)]);
     }
   }
-  return this.name;
 }