* Update to mojo 7d579155cc597aa3befcbfad66eef54bda06b57c

* Update to new API

We still need this for the observatory build.

This reverts commit 5082974b.

The engine.git repo doesn't need a copy of the Dart SDK anymore.

Fixes https://github.com/flutter/flutter/issues/2618

* Update to mojo 9a791294e429f9f2ca4f427796a284edb6f6768e

* Update to account for Mojo API changes

Roll dart to ccfd19bfd775c7cfc400aeda2c08fd821616cc82.

Update thread names in the Dart timeline.

Update Dart revision to pull in changes related to tracing and add more trace types to TracingController

The layout protocol in Mozart changed. Now we need to pipe a scene version
through the system to the compositor.

Fixes https://github.com/flutter/flutter/issues/2670

This reverts commit 7bfce5cb.
This reverts commit a550e7e3.

This required a bunch of changes because of the new sk_sp type Skia has
introduced into their API.

Also rolls Dart to include their Android x86 fixes.

@jason-simmons @chinmaygarde @abarth

This reverts commit ccd1c5ce, reversing
changes made to d4f97e4f.

This was requested by @johnmccutchan because this change broke the
analyzer, which only uses SDK version 1.14.1, since that's what we pull
in. He said he'd try again on Monday.