Remove checked-in .isolate files.

ui/gl/gl.isolate

-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# This isolate expresses the dependency on the default behavior of
-# Chromium's OpenGL binding layer. Many targets (in particular test
-# targets) that use graphics rely on this layer either implicitly or
-# explicitly, but not all of them need a direct dependency on ANGLE,
-# especially as ANGLE is being brought up on more platforms. This
-# isolate allows these targets to continue to use Chromium's default
-# graphics code path, while others can depend directly on ANGLE on
-# non-Windows platforms.
-{
-  # If includes were supported in conditions, we'd prefer to
-  # conditionally include angle.isolate here only on Windows, rather
-  # than introducing another isolate for ANGLE on multiple
-  # platforms. https://github.com/luci/luci-py/issues/230
-  'includes': [
-    '../../third_party/angle/angle.isolate',
-  ],
-}