Roll external/skia 914d319a0..26d8d77aa (12 commits)

https://skia.googlesource.com/skia.git/+log/914d319a0..26d8d77aa

2018-11-27 reed@google.com don't trust convexity with affine transforms
2018-11-27 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 471b8d4c7383..b980c5630eb5 (3 commits)
2018-11-27 kjlubick@google.com [canvaskit] Add shadow and save/restore support
2018-11-27 halcanary@google.com SkShaper->SkFont
2018-11-27 bsalomon@google.com Clamp GL_TEXTURE_MAX_LEVEL to 1 on Android.
2018-11-27 herb@google.com Add explicit to ctor
2018-11-27 rmistry@google.com Add new Android compile bot to CQ
2018-11-27 csmartdalton@google.com Don't let neighboring radii in GrAAFillRRectOp get too close
2018-11-27 reed@google.com Revert "Revert "migrate to passing paint/ctm for bounds""
2018-11-27 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 4ad2322aa9cf..67c93d206431 (1 commits)
2018-11-27 mtklein@google.com Reland "move decal_filter_scale inline, walk decal in 32.32""
2018-11-27 brianosman@google.com Remove tonalshadows GMs

The AutoRoll server is located here: https://autoroll-internal.skia.org/r/android-master-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

Test: Presubmit checks will test this change.
Change-Id: Ib33cb607e82d4c19633157eaafa0e43f4add8a46
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.