Make GrRectBlurEffect be analytical rather than use a texture LUT.

The math isn't that complex and the existing code has intergralization of
the profile size that makes getting the texture coords correct tricky
(and currently wrong).


Bug: skia:9319
Change-Id: Ic928737ce4c40d28ee0696c3628e914f35ffe371
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/233985
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
6 files changed