Canvas.concat takes a 16-element Float32List instead of an array.

sky/engine/core/painting/Matrix4.h

Index: sky/engine/core/painting/Matrix4.h
diff --git a/sky/engine/core/painting/Matrix4.h b/sky/engine/core/painting/Matrix4.h
new file mode 100644
index 0000000000000000000000000000000000000000..d36d2db5be43cbdeb3bdeb4d8b3a3e37a7cde283
--- /dev/null
+++ b/sky/engine/core/painting/Matrix4.h
@@ -0,0 +1,29 @@
+// 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.
+
+#ifndef SKY_ENGINE_CORE_PAINTING_MATRIX4_H_
+#define SKY_ENGINE_CORE_PAINTING_MATRIX4_H_
+
+#include "dart/runtime/include/dart_api.h"
+#include "sky/engine/tonic/dart_converter.h"
+#include "third_party/skia/include/core/SkMatrix.h"
+
+namespace blink {
+// Very simple wrapper for SkMatrix to add a null state.
+class Matrix4 {
+ public:
+  SkMatrix sk_matrix;
+  bool is_null;
+};
+
+template <>
+struct DartConverter<Matrix4> {
+  static Matrix4 FromArgumentsWithNullCheck(Dart_NativeArguments args,
+                                            int index,
+                                            Dart_Handle& exception);
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_MATRIX4_H_