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

LayoutTests/fast/js/resources/js-test-pre.js

Index: LayoutTests/fast/js/resources/js-test-pre.js
diff --git a/LayoutTests/fast/js/resources/js-test-pre.js b/LayoutTests/fast/js/resources/js-test-pre.js
index d2cfc497520653e022ffeb65cb8e91ba195ecf6a..aed7e2195b3e12f6b3e7821e8822ebe22823f4c4 100644
--- a/LayoutTests/fast/js/resources/js-test-pre.js
+++ b/LayoutTests/fast/js/resources/js-test-pre.js
@@ -72,10 +72,12 @@ var description, debug, successfullyParsed, errorMessage;
     if (!isWorker())
         insertStyleSheet();
 
-    self.onerror = function(message)
-    {
-        errorMessage = message;
-    };
+    if (!self.isOnErrorTest) {
+        self.onerror = function(message)
+        {
+            errorMessage = message;
+        };
+    }
 
 })();