Fix the bug for VertexAttrib{I}Pointer when no array buffer bound

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.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 6108 matching lines @@
                                                     long long offset) {
   if (isContextLost())
     return;
   if (index >= m_maxVertexAttribs) {
     synthesizeGLError(GL_INVALID_VALUE, "vertexAttribPointer",
                       "index out of range");
     return;
   }
   if (!validateValueFitNonNegInt32("vertexAttribPointer", "offset", offset))
     return;
-  if (!m_boundArrayBuffer) {
+  if (!m_boundArrayBuffer && offset != 0) {
     synthesizeGLError(GL_INVALID_OPERATION, "vertexAttribPointer",
-                      "no bound ARRAY_BUFFER");
+                      "no ARRAY_BUFFER is bound and offset is non-zero");
     return;
   }
 
   m_boundVertexArrayObject->setArrayBufferForAttrib(index,
                                                     m_boundArrayBuffer.get());
   contextGL()->VertexAttribPointer(
       index, size, type, normalized, stride,
       reinterpret_cast<void*>(static_cast<intptr_t>(offset)));
 }
 
@@ skipping 1667 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(
     HTMLCanvasElementOrOffscreenCanvas& result) const {
   if (canvas())
     result.setHTMLCanvasElement(canvas());
   else
     result.setOffscreenCanvas(offscreenCanvas());
 }
 
 }  // namespace blink