TRAC #21930

Renamed SwapChain11's textures and views to better represent if they are for the back buffer or offscreen texture.

Signed-off-by: Shannon Woods
Signed-off-by: Daniel Koch

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1537 736b8ea6-26fd-11df-bfd4-992fa37f6226