Resizing a window larger results in the newly exposed region being invalidated
but the old region is treated as valid. This can result in the old region no
longer updating. This has been observed on Windows 7 64-bit with Aero theme
using NVIDIA GeForce GTS 250 and driver version 301.42. Invalidate the entire
client window area when resetting the swap chain so that it updates properly.

Original bug report: https://bugreports.qt-project.org/browse/QTBUG-27822
Review: http://codereview.appspot.com/6812076/
Author: Jonathan Liu

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1458 736b8ea6-26fd-11df-bfd4-992fa37f6226