[BlackBerry] Should check if it's cached resource before download
https://bugs.webkit.org/show_bug.cgi?id=115101

Reviewed by Rob Buis.

Since main resource maybe cached, if user want to save the resource, we first check
if it's cached. If yes, don't need to initiate a fresh load again, but get the
cached resource data out to save.

RIM bug# 324003, internally reviewed by Charles Wei.

* WebCoreSupport/FrameLoaderClientBlackBerry.cpp:
(WebCore::FrameLoaderClientBlackBerry::convertMainResourceLoadToDownload):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149182 268f45cc-cd09-0410-ab3c-d52691b4dbfc