Added a map type parameter to Image11::map since it was always being mapped for writing but mipmap generation was reading.

TRAC #22927

Signed-off-by: Jamie Madill
Signed-off-by: Nicolas Capens
Author: Geoff Lang

git-svn-id: https://angleproject.googlecode.com/svn/branches/es3proto@2275 736b8ea6-26fd-11df-bfd4-992fa37f6226