Move context_menu_node_ to RenderFrameImpl since it's not used in RenderViewImpl anymore.

BUG=350550
R=nasko@chromium.org

Review URL: https://codereview.chromium.org/195123004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256310 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256310