IndexedDB: Attributes for a cursor "run past the end" should be undefined.

IndexedDB: Attributes for a cursor "run past the end" should be undefined.
https://bugs.webkit.org/show_bug.cgi?id=83492

Patch by Alec Flett <alecflett@chromium.org> on 2012-04-12
Reviewed by Ojan Vafai.

Source/WebCore:

This brings us up to spec with respect to when it's ok to call
cursor.continue() and the various behaviors around it:

If you call it more than once, continue() throws an exception.

The values of key/primaryKey/value are consistent, whether or not
continue has been called, meaning that if continue() results in
data being loaded from the backing store, that data does not
affect the cursor until the success callback has completed.

Calls to update() and delete() can happen before continue(), but
not afterwards.

Test: storage/indexeddb/cursor-continue-validity.html

* Modules/indexeddb/IDBCursor.cpp:
(WebCore::IDBCursor::IDBCursor):
(WebCore::IDBCursor::key):
(WebCore::IDBCursor::primaryKey):
(WebCore::IDBCursor::value):
(WebCore::IDBCursor::update):
(WebCore::IDBCursor::continueFunction):
(WebCore::IDBCursor::deleteFunction):
(WebCore::IDBCursor::setGotValue):
(WebCore):
* Modules/indexeddb/IDBCursor.h:
(IDBCursor):
* Modules/indexeddb/IDBRequest.cpp:
(WebCore::IDBRequest::onSuccess):
(WebCore::IDBRequest::dispatchEvent):

LayoutTests:

* storage/indexeddb/cursor-continue-validity-expected.txt: Added.
* storage/indexeddb/cursor-continue-validity.html: Added.
* storage/indexeddb/resources/cursor-continue-validity.js: Added.
* storage/indexeddb/resources/mozilla/cursors-expected.txt:
* storage/indexeddb/resources/shared.js:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114022 268f45cc-cd09-0410-ab3c-d52691b4dbfc