Add a defensive null check.
Add a defensive null check.

Apparently, we can sometimes have a null RenderView here.  This must
corresponse to a frame/document that has already been detached from
the page.

R=jorlow
BUG=36831
TEST=none

Review URL: http://codereview.chromium.org/661169

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@40121 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