Recognize WEBGL extensions on Firefox

tests/html/html.status

 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 interactive_test: Skip # Must be run manually.
 cross_frame_test: Skip # Test reloads itself. Issue 18558
 
 [ $compiler == none && ($runtime == dartium || $runtime == drt) ]
 
 mirrors_js_typed_interop_test: Fail # Missing expected failure (Issue 25044)
@@ skipping 323 matching lines @@
 websql_test/supported: Fail
 
 # 'html' tests import the HTML library, so they only make sense in
 # a browser environment.
 [ $runtime == vm || $runtime == dart_precompiled || $runtime == dart_app ]
 *: Skip
 
 [ $compiler == dart2js && ($runtime == drt || $runtime == ff) ]
 request_animation_frame_test: Skip # Async test hangs.
 
+[ $runtime == drt ]
+webgl_extensions_test: Skip # webgl does not work properly on DRT, which is 'headless'.
+
 [ $compiler == dart2js && $csp && ($runtime == drt || $runtime == safari || $runtime == ff || $runtime == chrome || $runtime == chromeOnAndroid) ]
 # Note: these tests are all injecting scripts by design.  This is not allowed under CSP.
+# TODO(sra): Change these tests to use a same-origin JavaScript script file.
 event_customevent_test: SkipByDesign
 js_interop_1_test: SkipByDesign
 js_test: SkipByDesign
 js_array_test: SkipByDesign
 js_typed_interop_test: SkipByDesign
 js_typed_interop_default_arg_test: SkipByDesign
 js_typed_interop_type_test: SkipByDesign
 js_function_getter_test: SkipByDesign
 js_function_getter_trust_types_test: SkipByDesign
 js_dart_to_string_test: SkipByDesign
@@ skipping 40 matching lines @@
 # These are raw dart:js tests that fail due to bugs in the CPS IR:
 js_test/Dart_functions: RuntimeError # Tree-shaking an escaping closure #25720
 
 [ $compiler == dart2js && $cps_ir && $host_checked ]
 js_typed_interop_default_arg_test/none: Crash # Issue 25911
 js_typed_interop_default_arg_test/default_value: Crash # Issue 25911
 js_typed_interop_default_arg_test/explicit_argument: Crash # Issue 25911
 
 [ $compiler == dart2js && $cps_ir && $checked ]
 *: Skip # `assert` not implemented