WebGL 2: add readPixels API to read pixels into pixel pack buffer

Source/modules/webgl/WebGLBuffer.cpp

 /*
  * 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 21 matching lines @@
 namespace blink {
 
 WebGLBuffer* WebGLBuffer::create(WebGLRenderingContextBase* ctx)
 {
     return new WebGLBuffer(ctx);
 }
 
 WebGLBuffer::WebGLBuffer(WebGLRenderingContextBase* ctx)
     : WebGLSharedPlatform3DObject(ctx)
     , m_initialTarget(0)
+    , m_size(0)
 {
     setObject(ctx->webContext()->createBuffer());
 }
 
 WebGLBuffer::~WebGLBuffer()
 {
     // See the comment in WebGLObject::detachAndDeleteObject().
     detachAndDeleteObject();
 }
 
 void WebGLBuffer::deleteObjectImpl(WebGraphicsContext3D* context3d)
 {
     context3d->deleteBuffer(m_object);
     m_object = 0;
 }
 
 void WebGLBuffer::setInitialTarget(GLenum target)
 {
     // WebGL restricts the ability to bind buffers to multiple targets based on
     // it's initial bind point.
     ASSERT(!m_initialTarget);
     m_initialTarget = target;
 }
 
 } // namespace blink