[heap] Move {hidden_string} into the root list.

src/factory.h

 // Copyright 2014 the V8 project 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 V8_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "src/isolate.h"
 #include "src/messages.h"
 
@@ skipping 607 matching lines @@
 #undef SYMBOL_ACCESSOR
 
   inline void set_string_table(Handle<StringTable> table) {
     isolate()->heap()->set_string_table(*table);
   }
 
   inline void set_weak_stack_trace_list(Handle<WeakFixedArray> list) {
     isolate()->heap()->set_weak_stack_trace_list(*list);
   }
 
-  Handle<String> hidden_string() {
-    return Handle<String>(&isolate()->heap()->hidden_string_);
-  }
-
   // Allocates a new SharedFunctionInfo object.
   Handle<SharedFunctionInfo> NewSharedFunctionInfo(
       Handle<String> name, int number_of_literals, FunctionKind kind,
       Handle<Code> code, Handle<ScopeInfo> scope_info,
       Handle<TypeFeedbackVector> feedback_vector);
   Handle<SharedFunctionInfo> NewSharedFunctionInfo(Handle<String> name,
                                                    MaybeHandle<Code> code);
 
   // Allocate a new type feedback vector
   template <typename Spec>
@@ skipping 85 matching lines @@
   // Reinitialize a JSProxy into an (empty) JS object of respective type and
   // size, but keeping the original prototype.  The receiver must have at least
   // the size of the new object.  The object is reinitialized and behaves as an
   // object that has been freshly allocated.
   void ReinitializeJSProxy(Handle<JSProxy> proxy, InstanceType type, int size);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_