Linux: fix crash when getting the screen info for a NULL window.
Linux: fix crash when getting the screen info for a NULL window.

Since we still have the hack where we pass raw pointers into the
renderer, we should catch the NULL case and return something sane.

Additionally, while I'm at it, always tell WebKit that it has a 32-bit
screen. Since it paints via IPC messages, it doesn't need to know what
the actual screen is using; we handle all that in the BackingStore.

Review URL: http://codereview.chromium.org/50030


git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@12167 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