Tighten OpenHandle's extra checks.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 128973094762b35a4f85d32e14c0364d1243d754..26a9c48e70a97630b6434dab51d54b8820799cf8 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2522,7 +2522,7 @@ class PropertyCallbackInfo {
  public:
   V8_INLINE Isolate* GetIsolate() const;
   V8_INLINE Local<Value> Data() const;
-  V8_INLINE Local<Object> This() const;
+  V8_INLINE Local<Value> This() const;
   V8_INLINE Local<Object> Holder() const;
   V8_INLINE ReturnValue<T> GetReturnValue() const;
   // This shouldn't be public, but the arm compiler needs it.
@@ -6495,8 +6495,8 @@ Local<Value> PropertyCallbackInfo<T>::Data() const {
 
 
 template<typename T>
-Local<Object> PropertyCallbackInfo<T>::This() const {
-  return Local<Object>(reinterpret_cast<Object*>(&args_[kThisIndex]));
+Local<Value> PropertyCallbackInfo<T>::This() const {
+  return Local<Value>(reinterpret_cast<Value*>(&args_[kThisIndex]));
 }