Fire window.onerror for uncaught IndexedDB errors

LayoutTests/storage/indexeddb/resources/intversion-upgrades.js

 if (this.importScripts) {
     importScripts('../../../resources/js-test.js');
     importScripts('shared.js');
 }
 
 description("Upgrade a database, open a second connection at the same version, ensure specifying a lower version causes an error");
 
 function test()
 {
     removeVendorPrefixes();
@@ skipping 85 matching lines @@
     evalAndLog("request.onerror = errorWhenTryingLowVersion");
     request.onblocked = unexpectedBlockedCallback;
     request.onsuccess = unexpectedSuccessCallback;
     request.onupgradeneeded = unexpectedUpgradeNeededCallback;
 }
 
 function errorWhenTryingLowVersion(evt)
 {
     preamble(evt);
     debug("request.error.message = " + request.error.message);
+    evt.preventDefault();
+
     evalAndLog("request = indexedDB.open(dbname, 4)");
     request.onblocked = unexpectedBlockedCallback;
     request.onerror = unexpectedErrorCallback;
     evalAndLog("request.onupgradeneeded = connection4UpgradeNeeded");
     evalAndLog("request.onsuccess = connection4Success");
 }
 
 var gotConnection4UpgradeNeeded = false;
 function connection4UpgradeNeeded(evt)
 {
@@ skipping 19 matching lines @@
 
 function connection5Success(evt)
 {
     preamble(evt);
     evalAndLog("db = event.target.result");
     shouldBe("db.version", "4");
     finishJSTest();
 }
 
 test();