IndexedDB: Have IDBCursor and IDBRequest explicitly break ref cycles

LayoutTests/storage/indexeddb/cursor-request-cycle-expected.txt

-Verify that that cursors accessed after being closed are well behaved
+Verify that that cursors weakly hold request, and work if request is GC'd
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
 indexedDB = self.indexedDB || self.webkitIndexedDB || self.mozIndexedDB || self.msIndexedDB || self.OIndexedDB;

[alecflett, 2013/09/06 17:56:35]

Not right now, but we really ought to scrub these from our tests...

[jsbell, 2013/09/06 18:07:43]

ISTR that we were waiting until the *reference* bots (running older Chrome) had
the prefix-less version. dgrogan@ - does that sound familiar? Any idea if we've
hit that milestone?

 
-dbname = "closed-cursor.html"
+dbname = "cursor-request-cycle.html"
 indexedDB.deleteDatabase(dbname)
 indexedDB.open(dbname)
 
 prepareDatabase():
 db = event.target.result
 store = db.createObjectStore('store')
-store.put({value: 'value'}, ['key'])
 
 onOpen():
 db = event.target.result
 tx = db.transaction('store')
 store = tx.objectStore('store')
 cursorRequest = store.openCursor()
+otherRequest = store.get(0)
 
-openCursorSuccess():
+openCursorRequest():
 cursor = cursorRequest.result
-Don't continue the cursor, so it retains its key/primaryKey/value
+PASS cursor is non-null.
+PASS cursor.key is "key1"
+PASS cursor.value is "value1"
 
-transactionComplete():
-PASS JSON.stringify(cursor.key) is "[\"key\"]"
-PASS JSON.stringify(cursor.primaryKey) is "[\"key\"]"
-PASS JSON.stringify(cursor.value) is "{\"value\":\"value\"}"
+otherRequestSuccess():
+PASS afterCount is beforeCount
+cursor.continue()
+finalRequest = store.get(0)
+
+finalRequestSuccess():
+PASS cursor.key is "key2"
+PASS cursor.value is "value2"
 PASS successfullyParsed is true
 
 TEST COMPLETE