Roll external/skia 1b5ece0f0..e70aed706 (1 commits)

https://skia.googlesource.com/skia.git/+log/1b5ece0f0..e70aed706

2018-09-12 angle-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com Roll third_party/externals/angle2 2da04538b4ff..8370e6bcb369 (3 commits)

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: I98dc5d75b134d77abf4002f47c4498a35da43150
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.