Make WebKitCSSMatrix an alias of DOMMatrix

third_party/WebKit/Source/core/css/BUILD.gn

 # Copyright 2016 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("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("css") {
   split_count = 5
   sources = [
     "ActiveStyleSheets.cpp",
@@ skipping 68 matching lines @@
     "CSSInheritedValue.cpp",
     "CSSInheritedValue.h",
     "CSSInitialValue.cpp",
     "CSSInitialValue.h",
     "CSSKeyframeRule.cpp",
     "CSSKeyframeRule.h",
     "CSSKeyframesRule.cpp",
     "CSSKeyframesRule.h",
     "CSSMarkup.cpp",
     "CSSMarkup.h",
-    "CSSMatrix.cpp",
-    "CSSMatrix.h",
     "CSSMediaRule.cpp",
     "CSSMediaRule.h",
     "CSSNamespaceRule.cpp",
     "CSSNamespaceRule.h",
     "CSSPageRule.cpp",
     "CSSPageRule.h",
     "CSSPaintImageGenerator.cpp",
     "CSSPaintImageGenerator.h",
     "CSSPaintValue.cpp",
     "CSSPaintValue.h",
@@ skipping 410 matching lines @@
     "resolver/TransformBuilder.h",
     "resolver/ViewportStyleResolver.cpp",
     "resolver/ViewportStyleResolver.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }