Add ANGLE revision to gclient config.

Bug: angleproject:3339
Change-Id: I1508937b5a367ed732231996c1b24588be5df9cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1549645
Auto-Submit: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>

recipes/recipe_modules/gclient/config.py

@@ -411,6 +411,7 @@ def angle(c):
   soln = c.solutions.add()
   soln.name = 'angle'
   soln.url = 'https://chromium.googlesource.com/angle/angle.git'
+  c.got_revision_mapping['angle'] = 'got_revision'
 
 @config_ctx()
 def dawn(c):