Fire window.onerror for uncaught IndexedDB errors

LayoutTests/storage/indexeddb/resources/metadata.js

 if (this.importScripts) {
     importScripts('../../../resources/js-test.js');
     importScripts('shared.js');
 }
 
 description("Test IndexedDB database metadata mutation/snapshotting");
 
 indexedDBTest(prepareDatabase, snapshotConnection1);
 function prepareDatabase()
 {
@@ skipping 52 matching lines @@
         evalAndLog("connection3store1.createIndex('index3', 'path')");
 
         shouldBe("connection3.version", "3");
         shouldBe("connection3.objectStoreNames.length", "3");
         shouldBe("connection3store1.indexNames.length", "3");
 
         trans.oncomplete = unexpectedCompleteCallback;
         debug("Connection's properties should be reverted on abort");
         evalAndLog("trans.abort()");
     };
-    request.onerror = function() {
+    request.onerror = function(evt) {
+        evt.preventDefault();
+
         debug("Connection's properties should be snapshotted on close");
         evalAndLog("connection3.close()");
         fourthOpen();
-    }
+    };
 }
 
 function fourthOpen()
 {
     debug("");
     debug("fourthOpen():");
     evalAndLog("request = indexedDB.open(dbname, 4)");
     request.onerror = unexpectedErrorCallback;
     request.onupgradeneeded = function() {
         evalAndLog("connection4 = request.result");
@@ skipping 33 matching lines @@
     shouldBe("connection3store1.indexNames.length", "2");
     debug("");
 
     shouldBe("connection4.version", "4");
     shouldBe("connection4.objectStoreNames.length", "3");
     shouldBe("connection4store1.indexNames.length", "3");
     debug("");
 
     finishJSTest();
 }