[SPv175][PE] Antialias clips for PaintChunks (and FloatClips)

ClipDisplayItems would use/generate antialiased clips, so it makes sense
to carry that bit (literally) forward.
Also update the FloatClip display item code-path for consistency.

Bug: 814876, 819617
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I1433804bd5734857116e613c2342c49d42499ecb
Reviewed-on: https://chromium-review.googlesource.com/934450
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541482}
173 files changed