V8 Binding: Introduce toNativeWithTypeCheck

Source/bindings/v8/custom/V8CanvasRenderingContext2DCustom.cpp

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 41 matching lines @@
         return toV8(style->canvasGradient(), creationContext, isolate);
 
     if (style->canvasPattern())
         return toV8(style->canvasPattern(), creationContext, isolate);
 
     return v8String(isolate, style->color());
 }
 
 static PassRefPtr<CanvasStyle> toCanvasStyle(v8::Handle<v8::Value> value, v8::Isolate* isolate)
 {
-    if (V8CanvasGradient::hasInstance(value, isolate))
-        return CanvasStyle::createFromGradient(V8CanvasGradient::toNative(v8::Handle<v8::Object>::Cast(value)));
-
-    if (V8CanvasPattern::hasInstance(value, isolate))
-        return CanvasStyle::createFromPattern(V8CanvasPattern::toNative(v8::Handle<v8::Object>::Cast(value)));
-
-    return 0;
+    RefPtr<CanvasStyle> canvasStyle = CanvasStyle::createFromGradient(V8CanvasGradient::toNativeWithTypeCheck(isolate, value));
+    if (canvasStyle)
+        return canvasStyle;
+    return CanvasStyle::createFromPattern(V8CanvasPattern::toNativeWithTypeCheck(isolate, value));
 }
 
 void V8CanvasRenderingContext2D::strokeStyleAttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     CanvasRenderingContext2D* impl = V8CanvasRenderingContext2D::toNative(info.Holder());
     v8SetReturnValue(info, toV8Object(impl->strokeStyle(), info.Holder(), info.GetIsolate()));
 }
 
 void V8CanvasRenderingContext2D::strokeStyleAttributeSetterCustom(v8::Local<v8::Value> value, const v8::PropertyCallbackInfo<void>& info)
 {
@@ skipping 13 matching lines @@
 void V8CanvasRenderingContext2D::fillStyleAttributeSetterCustom(v8::Local<v8::Value> value, const v8::PropertyCallbackInfo<void>& info)
 {
     CanvasRenderingContext2D* impl = V8CanvasRenderingContext2D::toNative(info.Holder());
     if (value->IsString())
         impl->setFillColor(toCoreString(value.As<v8::String>()));
     else
         impl->setFillStyle(toCanvasStyle(value, info.GetIsolate()));
 }
 
 } // namespace WebCore