DevTools: Do not crash on document-less HTMLFrameOwnerElement removal from DOM while inspecting.
DevTools: Do not crash on document-less HTMLFrameOwnerElement removal from DOM while inspecting.

BUG=13996
Review URL: http://codereview.chromium.org/126269

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@18609 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser