gpu: Make sure the fbo is always bound while the swap callback runs if an offscreen target is used.
gpu: Make sure the fbo is always bound while the swap callback runs if an offscreen target is used.

This didn't happen for non-multisampled offscreen targets that didn't have a parent.

BUG=58557
TEST=None

Review URL: http://codereview.chromium.org/3654002

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@62164 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