Explicitly test same/cross-origin importScripts() effect on worker.onerror.

LayoutTests/http/tests/resources/js-test-pre.js

 // svg/dynamic-updates tests set enablePixelTesting=true, as we want to dump text + pixel results
 if (self.testRunner)
     testRunner.dumpAsText(self.enablePixelTesting);
 
 var description, debug, successfullyParsed, errorMessage;
 
 (function() {
 
     function getOrCreate(id, tagName)
     {
@@ skipping 54 matching lines @@
     function insertStyleSheet()
     {
         var styleElement = document.createElement("style");
         styleElement.textContent = css;
         (document.head || document.documentElement).appendChild(styleElement);
     }
 
     if (!isWorker())
         insertStyleSheet();
 
-    self.onerror = function(message)
-    {
-        errorMessage = message;
-    };
+    if (!self.isOnErrorTest) {

[do-not-use, 2013/07/24 15:11:29]

nit: Should we update LayoutTests/fast/js/resources/js-test-pre.js as well for
consistency?

[do-not-use, 2013/07/24 15:11:29]

Should we update LayoutTests/fast/js/resources/js-test-pre.js as well for
consistency?

[Mike West, 2013/07/24 15:21:57]

We should, good idea. I'll add that.

+        self.onerror = function(message)
+        {
+            errorMessage = message;
+        };
+    }
 
 })();
 
 function isWorker()
 {
     // It's conceivable that someone would stub out 'document' in a worker so
     // also check for childNodes, an arbitrary DOM-related object that is
     // meaningless in a WorkerContext.
     return (typeof document === 'undefined' || typeof document.childNodes === 'undefined') && !!self.importScripts;
 }
@@ skipping 466 matching lines @@
     testPassed = function(msg) {
         workerPort.postMessage('PASS:' + msg);
     }
     finishJSTest = function() {
         workerPort.postMessage('DONE:');
     }
     debug = function(msg) {
         workerPort.postMessage(msg);
     }
 }