https://bugs.webkit.org/show_bug.cgi?id=121918

Reviewed by Alexey Proskuryakov.

Source/JavaScriptCore:

* Configurations/FeatureDefines.xcconfig:

Source/WebCore:

* Configurations/FeatureDefines.xcconfig:

(WebCore::IDBFactory::create): If the IDBFactoryBackend is null (which it is for on-levelDB platforms),
  don't create an IDBFactory. This hides the feature from javascript even though upport code is in the build.

* inspector/InspectorIndexedDBAgent.cpp: Empty out DatabaseLoader::execute on Mac until the inspector
  build gurus can figure out a 32bit-vs-64bit issue that there is no obvious solution for.

* WebCore.xcodeproj/project.pbxproj: Remove the Modules/indexedDB/leveldb directory now that Mac has no
  further use for it.

Source/WebKit/mac:

* Configurations/FeatureDefines.xcconfig:

Source/WebKit2:

* Configurations/FeatureDefines.xcconfig:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@156447 268f45cc-cd09-0410-ab3c-d52691b4dbfc