Change scratch texture cache behavior to only reuse scratch textures used as render targets if they will be reused as render targets.

The original behavior could sometimes confuse the driver; textures would alternate between being used as render targets and having data uploaded into them.
Review URL: https://codereview.appspot.com/6480049

git-svn-id: http://skia.googlecode.com/svn/trunk@5252 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed