Implement a bicubic resampling image filter, with raster and GPU backends.

Implement a bicubic resampling image filter, with raster and GPU backends.
In order to get this to work on the GPU side, I had to modify the width and height of the drawn texture in drawSprite() and drawDevice() to use the filtered texture's dimensions, instead of the source texture.  (This wasn't a problem before since all other image filters produce results the same dimensions as their input texture.)
For now, this implementation only does axis-aligned scaling (same as the Lanczos-3 implementation in Chrome).  It's also done for correctness and clarity, not speed, so there are lots of opportunities for speedups.

Review URL: https://codereview.appspot.com/7033049

git-svn-id: http://skia.googlecode.com/svn/trunk@7275 2bbb7eff-a529-9590-31e7-b0007b416f81