Bug 776389 - Find the source of scripts from the subscript loader correctly. r=bz

dom/base/nsJSEnvironment.cpp

@@ -3871,6 +3871,12 @@ ReadSourceFromFilename(JSContext *cx, const char *filename, jschar **src, PRUint
 {
   nsresult rv;
 
+  // mozJSSubScriptLoader prefixes the filenames of the scripts it loads with
+  // the filename of its caller. Axe that if present.
+  const char *arrow = strstr(filename, " -> ");
+  if (arrow)
+    filename = arrow + strlen(" -> ");
+
   // Get the URI.
   nsCOMPtr<nsIURI> uri;
   rv = NS_NewURI(getter_AddRefs(uri), filename);

js/xpconnect/tests/chrome/test_chrometoSource.xul

@@ -17,6 +17,7 @@
   <script type="application/javascript"><![CDATA[
 const Cu = Components.utils;
 Cu.import("resource://gre/modules/NetUtil.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
 
 function inlinefunction() {
          return 42;
@@ -29,7 +30,11 @@ is(src.charAt(src.length - 1), "}", "inline XUL source should end with '}'");
 src = outoflinefunction.toSource();
 isnot(src.indexOf("return 42"), -1, "out of line XUL script should have source")
 is(src.charAt(src.length - 1), "}", "out of line XUL source should end with '}'");
-src = NetUtil.asyncFetch.toSource()
+src = NetUtil.asyncFetch.toSource();
 isnot(src.indexOf("return"), -1, "JSM should have source");
+var ns = {};
+Services.scriptloader.loadSubScript("resource://gre/modules/NetUtil.jsm", ns);
+src = ns.NetUtil.asyncFetch.toSource();
+isnot(src.indexOf("return"), -1, "subscript should have source");
   ]]></script>
 </window>