Pass RenderFrameHost to WebContentsDelegate::HandleContextMenu. This is necessary in order to call RenderFrameHost::NotifyContextMenuClosed at a future time.

BUG=304341

Review URL: https://codereview.chromium.org/148843003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250116 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250116