Remove an unneeded local variable in FrameLoader::requestFromDelegate

It was removed after revision 148941.

BUG=None

Review URL: https://chromiumcodereview.appspot.com/23533008

git-svn-id: svn://svn.chromium.org/blink/trunk@156999 bbb929c8-8fbe-4397-9dbb-9b2b20218538