WebGL's SVGImage buffer should be cleared

Source/modules/webgl/WebGLRenderingContextBase.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * 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
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 469 matching lines @@
 
     // Check if each enabled vertex attribute is bound to a buffer.
     bool validateRenderingState(const char*);
 
     bool validateWebGLObject(const char*, WebGLObject*);
 
     // Adds a compressed texture format.
     void addCompressedTextureFormat(GLenum);
     void removeAllCompressedTextureFormats();
 
-    PassRefPtr<Image> drawImageIntoBuffer(Image*, int width, int height, const char* functionName);
+    PassRefPtr<Image> drawImageIntoBuffer(PassRefPtr<Image>, int width, int height, const char* functionName);
 
     PassRefPtr<Image> videoFrameToImage(HTMLVideoElement*);
 
     WebGLRenderbuffer* ensureEmulatedStencilBuffer(GLenum target, WebGLRenderbuffer*);
 
     // Structure for rendering to a DrawingBuffer, instead of directly
     // to the back-buffer of m_context.
     RefPtr<DrawingBuffer> m_drawingBuffer;
     DrawingBuffer* drawingBuffer() const;
 
@@ skipping 605 matching lines @@
     static IntSize oldestContextSize();
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif // WebGLRenderingContextBase_h