This is the ANGLE project, originally from https://chromium.googlesource.com/angle/angle 

The Mozilla upstream is the 'mozilla' branch from https://github.com/mozilla/angle, which
includes Mozilla-specific patches on top of upstream.

=== How to upgrade ANGLE ===

1. git clone https://github.com/mozilla/angle angle

2. Go into the angle dir, and add the google upstream as a remote:
     git remote add google https://chromium.googlesource.com/angle/angle

3. Fetch the new google upstream:
     git fetch google

4. Switch to the mozilla branch
     git checkout mozilla

5. Rebase the mozilla branch on top of the new google master.  Fix up patches along the way,
   remove unneded commits.
     git rebase -i google/master

6. Re-generate moz.build files:
     ./gyp_mozbuild

7. nuke mozilla-central/gfx/angle directory

8. copy all the relevant files from the github checkout
     cd mozilla-central
     mkdir gfx/angle
     cp -r /c/proj/angle/[A-Z]* /c/proj/angle/{include,src,moz.build} gfx/angle

9.  Build. Fix things until it builds.

10. Try runs and reviews!