Implement scale*() methods in DOMMatrix.

Source/core/dom/DOMMatrixReadOnly.idl

 // 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.
 
 [
     GarbageCollected,
     RuntimeEnabled=GeometryInterfaces,
 ] interface DOMMatrixReadOnly {
     // These attributes are simple aliases for certain elements of the 4x4 matrix
     readonly attribute unrestricted double a;
@@ skipping 21 matching lines @@
     readonly attribute unrestricted double m44;
 
     readonly attribute boolean is2D;
     readonly attribute boolean isIdentity;
 
     // FIXME: Should implement some methods (See: crbug.com/388780)
     // Immutable transform methods
     DOMMatrix translate(unrestricted double tx,
                         unrestricted double ty,
                         optional unrestricted double tz = 0);
+    DOMMatrix scale(unrestricted double scale,
+                    optional unrestricted double ox = 0,
+                    optional unrestricted double oy = 0);
+    DOMMatrix scale3d(unrestricted double scale,
+                      optional unrestricted double ox = 0,
+                      optional unrestricted double oy = 0,
+                      optional unrestricted double oz = 0);
+    DOMMatrix scaleNonUniform(unrestricted double sx,
+                              optional unrestricted double sy = 1,
+                              optional unrestricted double sz = 1,
+                              optional unrestricted double ox = 0,
+                              optional unrestricted double oy = 0,
+                              optional unrestricted double oz = 0);
 };