Remove unused testing files in Sky

sky/engine/platform/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 import("//sky/engine/build/scripts/scripts.gni")
 import("//sky/engine/config.gni")
 import("//testing/test.gni")
 
 # Most targets in this file are private actions so use that as the default.
@@ skipping 688 matching lines @@
     "geometry/RegionTest.cpp",
     "geometry/RoundedRectTest.cpp",
     "graphics/GraphicsContextTest.cpp",
     "graphics/ThreadSafeDataTransportTest.cpp",
     "graphics/filters/FilterOperationsTest.cpp",
     "graphics/filters/ImageFilterBuilderTest.cpp",
     "graphics/gpu/DrawingBufferTest.cpp",
     "image-decoders/ImageDecoderTest.cpp",
     "mac/ScrollElasticityControllerTest.mm",
     "network/HTTPParsersTest.cpp",
-    "testing/TreeTestHelpers.cpp",
-    "testing/TreeTestHelpers.h",
     "testing/RunAllTests.cpp",
     "transforms/TransformOperationsTest.cpp",
     "transforms/TransformationMatrixTest.cpp",
     "text/BidiResolverTest.cpp",
     "text/SegmentedStringTest.cpp",
     "text/UnicodeUtilitiesTest.cpp",
     "weborigin/KURLTest.cpp",
     "weborigin/SecurityPolicyTest.cpp",
   ]
 
@@ skipping 37 matching lines @@
     # See https://bugs.webkit.org/show_bug.cgi?id=62916.
     # TODO(GYP)
     #'cflags': ['-marm'],
     #    'conditions': [
     #      ['OS=="android"', {
     #        'cflags!': ['-mthumb'],
     #      }],
     #    ],
   }
 }