(remove SK_SUPPORT_LEGACY_TILED_BITMAPS)

Change-Id: Ic4552ede98e6690d3067695e01c90c81cb357cef
Reviewed-on: https://chromium-review.googlesource.com/545816
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488431}