Fixes https://github.com/flutter/flutter/issues/1576

We don't appear to need this DEPS entry to build.

Fixes in https://codereview.chromium.org/1673423004/

This reverts commit 3e7cf0b7.

This change lets us share base with mojo.git.

This reverts commit ca0342ac.

https://codereview.chromium.org/1571343003

This reverts commit eeafe3a5.

We had switched to libjpeg, but libjpeg was failing to decode images when
built with the defines in our .gn files

We don't use yasm, libjpeg_turbo, or mojo's devtools.

We don't need to run "pub get" anymore because we don't have any real Dart
packages in this repo anymore.

during precompilation