[devtools] create devtools-frontend gclient config

devtools-frontend is missing from gclient configs, causing the breakage:
https://ci.chromium.org/p/devtools-frontend/builders/ci/DevTools%20Linux/b8904421330390983280

This CL creates the devtools-frontend configuration

R=tandrii@chromium.org
TBR=machenbach@chromium.org
CC=yangguo@chromium.org

Bug: chromium:995657
Change-Id: I8e5ffce16f2b8f69931a71cd67a709427d1f42ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1765591Reviewed-by: Tamer Tas <tmrts@chromium.org>
Auto-Submit: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Tamer Tas <tmrts@chromium.org>

recipes/README.recipes.md

@@ -981,7 +981,7 @@ Raises:
 
 [DEPS](/recipes/recipe_modules/gclient/examples/full.py#5): [gclient](#recipe_modules-gclient), [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/step][recipe_engine/recipe_modules/step]
 
-— **def [RunSteps](/recipes/recipe_modules/gclient/examples/full.py#52)(api):**
+— **def [RunSteps](/recipes/recipe_modules/gclient/examples/full.py#53)(api):**
 ### *recipes* / [gclient:tests/patch\_project](/recipes/recipe_modules/gclient/tests/patch_project.py)
 
 [DEPS](/recipes/recipe_modules/gclient/tests/patch_project.py#9): [gclient](#recipe_modules-gclient), [recipe\_engine/buildbucket][recipe_engine/recipe_modules/buildbucket], [recipe\_engine/properties][recipe_engine/recipe_modules/properties]

recipes/recipe_modules/gclient/config.py

@@ -442,3 +442,10 @@ def openscreen(c):
   s.name = 'openscreen'
   s.url = 'https://chromium.googlesource.com/openscreen'
   c.got_revision_mapping['openscreen'] = 'got_revision'
+
+@config_ctx()
+def devtools(c):
+  s = c.solutions.add()
+  s.name = 'devtools'
+  s.url = 'https://chromium.googlesource.com/devtools/devtools-frontend.git'
+  c.got_revision_mapping['devtools'] = 'got_revision'

recipes/recipe_modules/gclient/examples/full.py

@@ -37,6 +37,7 @@ TEST_CONFIGS = [
   'luci_py',
   'master_deps',
   'nacl',
+  'devtools',
   'openscreen',
   'pdfium',
   'recipes_py',