[Oilpan] Migrate classes under module/webgl onto oilpan heap

Source/modules/webgl/WebGLSampler.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebGLSampler_h
 #define WebGLSampler_h
 
 #include "modules/webgl/WebGLSharedPlatform3DObject.h"
-#include "wtf/PassRefPtr.h"
 
 namespace blink {
 
 class WebGL2RenderingContextBase;
 
 class WebGLSampler : public WebGLSharedPlatform3DObject {
     DEFINE_WRAPPERTYPEINFO();
 public:
     ~WebGLSampler() override;
 
-    static PassRefPtrWillBeRawPtr<WebGLSampler> create(WebGL2RenderingContextBase*);
+    static WebGLSampler* create(WebGL2RenderingContextBase*);
 
 protected:
     explicit WebGLSampler(WebGL2RenderingContextBase*);
 
     void deleteObjectImpl(WebGraphicsContext3D*) override;
 
 private:
     bool isSampler() const override { return true; }
 };
 
 } // namespace blink
 
 #endif // WebGLSampler_h