Allow blitting to a render texture in BlitFramebuffer. Change the type check to allow blitting between render buffers and render textures. Store the format for render textures so that resolving to a render texture Colorbuffer will pass the format check. BUG=37 Review URL: http://codereview.appspot.com/2205043 git-svn-id: https://angleproject.googlecode.com/svn/trunk@430 736b8ea6-26fd-11df-bfd4-992fa37f6226