Adds filter support for offscreen canvas

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.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.
 
 // https://html.spec.whatwg.org/multipage/scripting.html#the-offscreen-2d-rendering-context
 
 [
     Exposed=(Window,Worker),
     RuntimeEnabled=ExperimentalCanvasFeatures,
 ] interface OffscreenCanvasRenderingContext2D {
@@ skipping 10 matching lines @@
     void scale(unrestricted double x, unrestricted double y);
     void rotate(unrestricted double angle);
     void translate(unrestricted double x, unrestricted double y);
     void transform(unrestricted double a, unrestricted double b, unrestricted double c, unrestricted double d, unrestricted double e, unrestricted double f);
     void setTransform(unrestricted double a, unrestricted double b, unrestricted double c, unrestricted double d, unrestricted double e, unrestricted double f);
     void resetTransform();
 
     // compositing
     attribute unrestricted double globalAlpha; // (default 1.0)
     attribute DOMString globalCompositeOperation; // (default source-over)
-    [Exposed=Window] attribute DOMString filter;
+    attribute DOMString filter;
 
     // image smoothing
     attribute boolean imageSmoothingEnabled; // (default True)
     attribute ImageSmoothingQuality imageSmoothingQuality; // (default "low")
 
     // colors and styles
     attribute (DOMString or CanvasGradient or CanvasPattern) strokeStyle; // (default black)
     attribute (DOMString or CanvasGradient or CanvasPattern) fillStyle; // (default black)
     CanvasGradient createLinearGradient(double x0, double y0, double x1, double y1);
     [RaisesException] CanvasGradient createRadialGradient(double x0, double y0, double r0, double x1, double y1, double r1);
@@ skipping 41 matching lines @@
     attribute DOMString lineJoin; // "round", "bevel", "miter" (default "miter")
     attribute unrestricted double miterLimit; // (default 10)
 
     // dashed lines
     void setLineDash(sequence<unrestricted double> dash);
     sequence<unrestricted double> getLineDash();
     attribute unrestricted double lineDashOffset;
 };
 
 OffscreenCanvasRenderingContext2D implements CanvasPathMethods;