Make OffscreenCanvasRenderingContext2D renderable on a worker

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl

Index: third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl
diff --git a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl
index 5c33a575d9ff207ad3753de515edbbc2430d3c0e..7e71cb85b1c5ca7e47d0600b9d4bb6fc4a5b01f5 100644
--- a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl
+++ b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.idl
@@ -11,6 +11,15 @@
 ] interface OffscreenCanvasRenderingContext2D {
     // back-reference to the canvas
     readonly attribute OffscreenCanvas offscreenCanvas;
+
+    // colors and styles (see also the CanvasDrawingStyles interface)
+    attribute (DOMString or CanvasGradient or CanvasPattern) strokeStyle; // (default black)
+    attribute (DOMString or CanvasGradient or CanvasPattern) fillStyle; // (default black)
+
+    //CanvasRect interface
+    void clearRect(unrestricted double x, unrestricted double y, unrestricted double width, unrestricted double height);
+    void fillRect(unrestricted double x, unrestricted double y, unrestricted double width, unrestricted double height);
+    void strokeRect(unrestricted double x, unrestricted double y, unrestricted double width, unrestricted double height);
 };
 
 OffscreenCanvasRenderingContext2D implements CanvasPathMethods;