LayoutTests/resources/js-test.js onerror tweak.

LayoutTests/fast/dom/Geolocation/script-tests/callback-exception.js

 description("Tests that when an exception is thrown in the success callback, the error callback is not invoked. Note that this test throws an exception which is not caught.");
 
 var mockLatitude = 51.478;
 var mockLongitude = -0.166;
 var mockAccuracy = 100;
 
 if (window.testRunner) {
     testRunner.setGeolocationPermission(true);
     testRunner.setMockGeolocationPosition(mockLatitude,
                                                     mockLongitude,
                                                     mockAccuracy);
 } else
     debug('This test can not be run without the testRunner');
 
 var position;
 navigator.geolocation.getCurrentPosition(function(p) {
     position = p;
     shouldBe('position.coords.latitude', 'mockLatitude');
     shouldBe('position.coords.longitude', 'mockLongitude');
     shouldBe('position.coords.accuracy', 'mockAccuracy');
 
     // Yield to allow for the error callback to be invoked. The timer
     // must be started before the exception is thrown.
     window.setTimeout(assertWeGotException, 0);
+    expectError();
     throw new Error('Exception in success callback');
 }, function(e) {
     testFailed('Error callback invoked unexpectedly');
     finishJSTest();
 });
 
 function assertWeGotException()
 {
     shouldHaveHadError();
     finishJSTest();
 }
 
 window.jsTestIsAsync = true;