Scale up non-multiple-of-4 dxt textures

D3D doesn't support DXT textures that aren't a multiple of 4 in size, so multiply the sizes by 2 or 4 so they work. Then ensure sampler parameters are set up correctly so they don't sample the unuploaded miplevels.

BUG=https://code.google.com/p/angleproject/issues/detail?id=237
TEST=

Review URL: https://codereview.appspot.com/6287045

git-svn-id: http://angleproject.googlecode.com/svn/trunk@1222 736b8ea6-26fd-11df-bfd4-992fa37f6226
5 files changed