Munch the incoming inverse to force nearly-no-scale to no-scale, if we think the cheat won't be noticed. This allows us to take a fast case if the caller gave us a matrix scale of (for instance) 1.0000001 instead of 1.0
Munch the incoming inverse to force nearly-no-scale to no-scale, if we think
the cheat won't be noticed. This allows us to take a fast case if the caller
gave us a matrix scale of (for instance) 1.0000001 instead of 1.0

drawBitmap already has this logic, it just wasn't ever propogated to bitmapShader before.
Review URL: https://codereview.appspot.com/6720052

csulmone/skia,csulmone/skia,csulmone/skia,csulmone/skia