Implemented/Tested line-drawing functions in OffscreenCanvas 2D Context

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.
 
 // Note: The official spec is WIP at wiki.whatwg.org/wiki/OffscreenCanvas.
 
 [
     GarbageCollected,
     Exposed=(Window,Worker),
     RuntimeEnabled=ExperimentalCanvasFeatures,
 ] interface OffscreenCanvasRenderingContext2D {
     // back-reference to the canvas
     [ImplementedAs=getOffscreenCanvas] readonly attribute OffscreenCanvas offscreenCanvas;
 
-    // colors and styles (see also the CanvasDrawingStyles interface)
+    // colors and styles
     attribute (DOMString or CanvasGradient or CanvasPattern) strokeStyle; // (default black)
     attribute (DOMString or CanvasGradient or CanvasPattern) fillStyle; // (default black)
 
-    //CanvasRect interface
+    // 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);
+
+    // Path API (See BaseRenderingContext2D)
+    void beginPath();
+    void fill(optional CanvasFillRule winding);
+    void fill(Path2D path, optional CanvasFillRule winding);
+    void stroke();
+    void stroke(Path2D path);
+
+    // Line caps/joins
+    attribute unrestricted double lineWidth; // (default 1)
+    attribute DOMString lineCap; // "butt", "round", "square" (default "butt")
+    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;