[Oilpan] Remove a GC_PLUGIN_IGNORE

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 1062 matching lines @@
     // they will be freed before the last context is removed from the context group.
     m_boundArrayBuffer = nullptr;
     m_defaultVertexArrayObject = nullptr;
     m_boundVertexArrayObject = nullptr;
     m_vertexAttrib0Buffer = nullptr;
     m_currentProgram = nullptr;
     m_framebufferBinding = nullptr;
     m_renderbufferBinding = nullptr;
     m_valuebufferBinding = nullptr;
 
+    // WebGLTexture shared objects will be detached and deleted
+    // m_contextGroup->removeContext(this), which will bring about deleteTexture() calls.
+    // We null these out to avoid accessing those members in deleteTexture().
     for (size_t i = 0; i < m_textureUnits.size(); ++i) {
         m_textureUnits[i].m_texture2DBinding = nullptr;
         m_textureUnits[i].m_textureCubeMapBinding = nullptr;
         m_textureUnits[i].m_texture3DBinding = nullptr;
         m_textureUnits[i].m_texture2DArrayBinding = nullptr;
     }
 
     m_blackTexture2D = nullptr;
     m_blackTextureCubeMap = nullptr;
 
@@ skipping 5606 matching lines @@
 
     return totalBytesPerPixel;
 }
 
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 
 } // namespace blink