Roll Skia from 126788e087af to 31df6806c06b (6 revisions)

https://skia.googlesource.com/skia.git/+log/126788e087af..31df6806c06b

2021-07-30 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2021-07-30 herb@google.com draw atlas: using skvm
2021-07-30 johnstiles@google.com Reduce size of ChildPtr object.
2021-07-30 johnstiles@google.com Fixup enum name in SkFlattenable.
2021-07-30 johnstiles@google.com Create test case to repro skia:12212.
2021-07-30 rohitrao@google.com Removes a deprecated call to CTGetCoreTextVersion() when compiling for iOS 14+.

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 scroggo@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/+doc/main/autoroll/README.md

Test: Presubmit checks will test this change.
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.
Bug: b/186777432
Change-Id: Ie54ee7c8ff8e9929b937ead9947efb04bb849a96