Convert everything in the Sky API from degrees to radians.

sky/engine/core/painting/Path.idl

 // 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.
 
 [
   Constructor(),
   ImplementedAs=CanvasPath,
 ] interface Path {
     void moveTo(float x, float y);
     void lineTo(float x, float y);
-    void arcTo(Rect rect, float startAngle, float sweepAngle, boolean forceMoveTo);
+    void arcTo(Rect rect, float startAngle, float sweepAngle, boolean forceMoveTo); // angles in radians
     void close();
 };