Disable WebGL 2.0 conformance tests on debug bots.

content/test/gpu/generate_buildbot_json.py

Index: content/test/gpu/generate_buildbot_json.py
diff --git a/content/test/gpu/generate_buildbot_json.py b/content/test/gpu/generate_buildbot_json.py
index f9f9080bbeee3b7fa7b8d8867593675577bf437c..ddf41c6256cea5bf04792dd3841e7795f35e0746 100755
--- a/content/test/gpu/generate_buildbot_json.py
+++ b/content/test/gpu/generate_buildbot_json.py
@@ -808,6 +808,9 @@ TELEMETRY_TESTS = {
     'tester_configs': [
       {
         'allow_on_mac_nvidia': True,
+         # The WebGL 2.0 conformance tests take over an hour to run on
+         # the Debug bots, which is too long.
+        'build_configs': ['Release', 'Release_x64'],
         'fyi_only': True,
         'run_on_optional': True,
       },