Make OffscreenCanvasRenderingContext2D renderable on a worker

third_party/WebKit/Source/modules/canvas2d/CanvasStyle.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 51 matching lines @@
 }
 
 bool parseColorOrCurrentColor(Color& parsedColor, const String& colorString, HTMLCanvasElement* canvas)
 {
     ColorParseResult parseResult = parseColor(parsedColor, colorString);
     switch (parseResult) {
     case ParsedRGBA:
     case ParsedSystemColor:
         return true;
     case ParsedCurrentColor:
-        parsedColor = currentColor(canvas);
+        parsedColor = canvas ? currentColor(canvas) : Color::black;
         return true;
     case ParseFailed:
         return false;
     default:
         ASSERT_NOT_REACHED();
         return false;
     }
 }
 
 CanvasStyle::CanvasStyle(RGBA32 rgba)
@@ skipping 51 matching lines @@
     return Color::black;
 }
 
 DEFINE_TRACE(CanvasStyle)
 {
     visitor->trace(m_gradient);
     visitor->trace(m_pattern);
 }
 
 } // namespace blink