Refactor GLFunctorDrawable to use new SkCanvas API for clip region

Refactor GLFunctorDrawable::onDraw to get SkCanvas clip region
with new Skia API (getClipStack is going to be deprecated).

Test: Built and ran angler-userdebug. Ran CTS WebView clip tests.
Change-Id: Ia11e3f3d64d5c33802b7a8f296f213ef39a69905
1 file changed