Added runtime checks for GetClientRect errors.

I noticed that if the window handle is invalid, the resulting rect will be uninitialized. This change makes it fail immediately.

Review URL: http://codereview.appspot.com/2009042

git-svn-id: http://angleproject.googlecode.com/svn/trunk@386 736b8ea6-26fd-11df-bfd4-992fa37f6226
1 file changed