Revert 126719 - IndexedDB: Fix prefetching; cache was always being bypassed.

Regression introduced in r119183 when "Null" and "Invalid" were disambiguated.

Tests will require refactoring; tracked as crbug.com/118033

BUG=117920

Review URL: http://codereview.chromium.org/9691021

TBR=jsbell@chromium.org
Review URL: https://chromiumcodereview.appspot.com/9704039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126752 0039d316-1c4b-4281-b951-d872f2087c98

content/common/indexed_db/proxy_webidbcursor_impl.cc

@@ -67,7 +67,7 @@ void RendererWebIDBCursorImpl::continueFunction(const WebIDBKey& key,
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance();
 
-  if (key.type() == WebIDBKey::NullType) {
+  if (key.type() == WebIDBKey::InvalidType) {
     // No key, so this would qualify for a prefetch.
     ++continue_count_;