Revert[2] of "switch to isABitmap, deprecate SK_SUPPORT_LEGACY_SHADERBITMAPTYPE"

master-skia has been updated to use isABitmap

This reverts commit ff390c9bdd852405d9dc0fd5e384b1f935d8df08.

BUG=skia:

Review URL: https://codereview.chromium.org/1310573008
6 files changed