Improve performance in Surface::swap

TRAC #12145

- Create the flip RT texture once.
- Use state blocks for swap and restore all previous state.

Signed-off-by: Nicolas Capens
Signed-off-by: Daniel Koch

Author:    Andrew Lewycky

git-svn-id: http://angleproject.googlecode.com/svn/trunk@256 736b8ea6-26fd-11df-bfd4-992fa37f6226
2 files changed