Add 'error' parameter to 'window.onerror' handlers.

LayoutTests/fast/events/window-onerror-12-expected.txt

 CONSOLE MESSAGE: line 17: 1
 CONSOLE MESSAGE: line 17: 2
 CONSOLE MESSAGE: line 17: 3
 This test should trigger 'window.onerror' for the exception in the attribute handler, regardless of how it's set.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
 window.onerror: "Uncaught TypeError: Cannot call method 'mu' of null" at window-onerror-12.html (Line: 12, Column: 74)
+Stack Trace:
+TypeError: Cannot call method 'mu' of null
+    at HTMLButtonElement.onclick window-onerror-12.html:12:123
+    at window-onerror-12.html:33:24
+
 Returning 'true': the error should not be reported in the console as an unhandled exception.
+
+
+
 window.onerror: "Uncaught TypeError: Cannot call method 'mu' of null" at window-onerror-12.html (Line: 35, Column: 74)
+Stack Trace:
+TypeError: Cannot call method 'mu' of null
+    at HTMLButtonElement.onclick window-onerror-12.html:35:104
+    at window-onerror-12.html:33:24
+
 Returning 'true': the error should not be reported in the console as an unhandled exception.
+
+
+
 window.onerror: "Uncaught TypeError: Cannot call method 'mu' of null" at window-onerror-12.html (Line: 35, Column: 74)
+Stack Trace:
+TypeError: Cannot call method 'mu' of null
+    at HTMLButtonElement.onclick window-onerror-12.html:35:104
+    at window-onerror-12.html:33:24
+
 Returning 'true': the error should not be reported in the console as an unhandled exception.
+
+
+
 PASS successfullyParsed is true
 
 TEST COMPLETE
 Button.  Button 2 Button 3