No implicit conversion between a Foo** and a Handle<Foo>.

src/handles.h

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 24 matching lines @@
 
 // ----------------------------------------------------------------------------
 // A Handle provides a reference to an object that survives relocation by
 // the garbage collector.
 // Handles are only valid within a HandleScope.
 // When a handle is created for an object a cell is allocated in the heap.
 
 template<class T>
 class Handle {
  public:
-  INLINE(Handle(T** location)) { location_ = location; }
+  INLINE(explicit Handle(T** location)) { location_ = location; }
   INLINE(explicit Handle(T* obj));
 
   INLINE(Handle()) : location_(NULL) {}
 
   // Constructor for handling automatic up casting.
   // Ex. Handle<JSFunction> can be passed when Handle<Object> is expected.
   template <class S> Handle(Handle<S> handle) {
 #ifdef DEBUG
     T* a = NULL;
     S* b = NULL;
@@ skipping 320 matching lines @@
  private:
   bool has_been_transformed_;  // Tells whether the object has been transformed.
   int unused_property_fields_;  // Captures the unused number of field.
   Handle<JSObject> object_;    // The object being optimized.
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_