Fire window.onerror for uncaught IndexedDB errors

LayoutTests/storage/indexeddb/resources/intversion-revert-on-abort.js

 if (this.importScripts) {
     importScripts('../../../resources/js-test.js');
     importScripts('shared.js');
 }
 
 description("Test that integer versions are reverted when their version transactions abort.");
 
 function test()
 {
     removeVendorPrefixes();
@@ skipping 37 matching lines @@
     preamble(evt);
     evalAndLog("db = event.target.result");
     evalAndLog("db.createObjectStore('some os 2')");
     evalAndLog("event.target.transaction.abort()");
 }
 
 function errorAfterAbortCallback(evt)
 {
     preamble(evt);
     shouldBe("db.version", "2");
+    evt.preventDefault();
+
     evalAndLog("request = indexedDB.open(dbname)");
     evalAndLog("request.onsuccess = finalSuccessCallback");
     request.onerror = unexpectedErrorCallback;
     request.onblocked = unexpectedBlockedCallback;
     request.onupgradeneeded = unexpectedUpgradeNeededCallback;
 }
 
 function finalSuccessCallback(evt)
 {
     preamble(evt);
     evalAndLog("db = event.target.result");
     shouldBe("db.version", "2");
     shouldBe("db.objectStoreNames.length", "1");
     shouldBeEqualToString("db.objectStoreNames[0]", "some os");
     finishJSTest();
 }
 
 test();