Roll external/skia c88d1774ed50..b9f208817c76 (6 commits)

https://skia.googlesource.com/skia.git/+log/c88d1774ed50..b9f208817c76

2019-11-08 mtklein@google.com convert SkVMBlitter over to floats
2019-11-08 csmartdalton@google.com Always attach stencil buffers with exact sample count matches
2019-11-08 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-11-08 jlavrova@google.com Fixing no icu situation
2019-11-08 reed@google.com add flatten test to SkFont
2019-11-08 csmartdalton@google.com Defer stencil attachment until opsTask execution

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://skia-autoroll.corp.goog/r/android-master-autoroll
Please CC stani@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

Test: Presubmit checks will test this change.
Change-Id: I57b795ac7b2d2804164d4f8c699918651cf5f3cd
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.