TRAC #11321

Context owns incomplete textures of each texture type.
Also fix completeness determination: check minfilter to see if mipmapping is on.

Author:    Andrew Lewycky
Signed-off-by: Shannon Woods
Signed-off-by: Daniel Koch

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