Align IndexedDB metadata rollback on transaction abort to spec.

third_party/WebKit/LayoutTests/storage/indexeddb/resources/rename-common.js

 // Returns an IndexedDB database name likely to be unique to the test case.
 const databaseName = (testCase) => {
     return 'db' + self.location.pathname + '-' + testCase.name;
 };
 
 // Creates an EventWatcher covering all the events that can be issued by
 // IndexedDB requests and transactions.
 const requestWatcher = (testCase, request) => {
     return new EventWatcher(testCase, request,
         ['error', 'success', 'upgradeneeded']);
@@ skipping 57 matching lines @@
 // Returns a promise that resolves to an IndexedDB database. The caller must
 // close the database.
 const createDatabase = (testCase, setupCallback) => {
     const request = indexedDB.deleteDatabase(databaseName(testCase));
     const eventWatcher = requestWatcher(testCase, request);
 
     return eventWatcher.wait_for('success').then(event =>
         migrateDatabase(testCase, 1, setupCallback));
 };
 
+// Opens an IndexedDB database without performing schema changes.
+//
+// The given version number must match the database's current version.
+//
+// Returns a promise that resolves to an IndexedDB database. The caller must
+// close the database.
+const openDatabase = (testCase, version) => {
+    const request = indexedDB.open(databaseName(testCase), version);

[jsbell, 2016/09/16 18:17:28]

Maybe add onupgradeneeded = testCase.unreached_func(' ... '); ?

[pwnall, 2016/09/17 01:34:21]

I thought EventWatcher is supposed to reject its promise if it receives any
event that doesn't match the expectation list. [1] says "EventWatcher will
assert if an event occurs while there is no wait_for() created Promise waiting
to be fulfilled, or if the event is of a different type to the type currently
expected. This ensures that only the events that are expected occur, in the
correct order, and with the correct timing."

[1] https://github.com/w3c/testharness.js/blob/master/docs/api.md

+    const eventWatcher = requestWatcher(testCase, request);
+    return eventWatcher.wait_for('success').then(
+        event => event.target.result);
+}
+
 // The data in the 'books' object store records in the first example of the
 // IndexedDB specification.
 const BOOKS_RECORD_DATA = [
     { title: 'Quarry Memories', author: 'Fred', isbn: 123456 },
     { title: 'Water Buffaloes', author: 'Fred', isbn: 234567 },
     { title: 'Bedrock Nights', author: 'Barney', isbn: 345678 },
 ];
 
 // Creates a 'books' object store whose contents closely resembles the first
 // example in the IndexedDB specification.
@@ skipping 90 matching lines @@
 // is using it incorrectly.
 const checkTitleIndexContents = (testCase, index, errorMessage) => {
     const request = index.get(BOOKS_RECORD_DATA[2].title);
     const eventWatcher = requestWatcher(testCase, request);
     return eventWatcher.wait_for('success').then(() => {
         const result = request.result;
         assert_equals(result.isbn, BOOKS_RECORD_DATA[2].isbn, errorMessage);
         assert_equals(result.author, BOOKS_RECORD_DATA[2].author, errorMessage);
     });
 };