Trac #12375
This patch stores the current READ/DRAW and display in the context and
allows these eglGets to work.

Original-Author: Jim Hauxwell <james@dattrax.co.uk>
Signed-off-by: Nicolas Capens
Signed-off-by: Daniel Koch

git-svn-id: https://angleproject.googlecode.com/svn/trunk@321 736b8ea6-26fd-11df-bfd4-992fa37f6226