Roll ios/third_party/earl_grey b8f1ed850b..2fd8a7d4b7.

This provides support to build with deployment target 10.0.

Bug: 774724, 774726
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ic6445cb9bb788fbc92b90caa511473ea2ad963c6
Reviewed-on: https://chromium-review.googlesource.com/753645
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: Mike Baxley <baxley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513844}