Support pkg install step for Xcode 9 hermetic.

Xcode 9's actool depends on the Simulator being properly installed, which means
the proper Xcode run first launch step needs to be called.

This depends on a puppet change to allow calling xcodebuild -runFirstLaunch

Bug: 736060
Change-Id: Idc00a0d6079999ddb95362cf4204ba577f7fb022
Reviewed-on: https://chromium-review.googlesource.com/612471
Commit-Queue: Justin Cohen <[email protected]>
Reviewed-by: Sergey Berezin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#493953}
1 file changed