Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp

Index: Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp
diff --git a/Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp b/Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp
index dcb7e53ac450e13e6dce076a4006d7437cfd5437..d6934b2574ce41f77365b86898d53e210bff9c85 100644
--- a/Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp
+++ b/Source/core/html/canvas/WebGLVertexArrayObjectOES.cpp
@@ -40,7 +40,7 @@ WebGLVertexArrayObjectOES::WebGLVertexArrayObjectOES(WebGLRenderingContext* ctx,
     : WebGLContextObject(ctx)
     , m_type(type)
     , m_hasEverBeenBound(false)
-    , m_boundElementArrayBuffer(0)
+    , m_boundElementArrayBuffer(nullptr)
 {
     ScriptWrappable::init(this);
     m_vertexAttribState.resize(ctx->maxVertexAttribs());
@@ -115,14 +115,14 @@ void WebGLVertexArrayObjectOES::unbindBuffer(PassRefPtr<WebGLBuffer> buffer)
 {
     if (m_boundElementArrayBuffer == buffer) {
         m_boundElementArrayBuffer->onDetached(context()->webGraphicsContext3D());
-        m_boundElementArrayBuffer = 0;
+        m_boundElementArrayBuffer = nullptr;
     }
 
     for (size_t i = 0; i < m_vertexAttribState.size(); ++i) {
         VertexAttribState& state = m_vertexAttribState[i];
         if (state.bufferBinding == buffer) {
             buffer->onDetached(context()->webGraphicsContext3D());
-            state.bufferBinding = 0;
+            state.bufferBinding = nullptr;
         }
     }
 }