[CSS Typed OM] Make CSSRotation attributes mutable.

third_party/WebKit/Source/core/css/cssom/CSSRotation.idl

 // 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.
 
 // Represents a rotation value in a CSSTransformValue used for properties like
 // "transform".
 // Spec: https://drafts.css-houdini.org/css-typed-om/#cssrotation
 [
     Constructor(CSSNumericValue angleValue),
     Constructor(double x, double y, double z, CSSNumericValue angle),
     Exposed=(Window,PaintWorklet),
     RuntimeEnabled=CSSTypedOM,
     RaisesException=Constructor
 ] interface CSSRotation : CSSTransformComponent {
-    readonly attribute CSSNumericValue angle;
-    readonly attribute double x;
-    readonly attribute double y;
-    readonly attribute double z;
+    [RaisesException=Setter] attribute CSSNumericValue angle;
+    attribute double x;
+    attribute double y;
+    attribute double z;
 };