v8::Private::ForApi should be context-independent.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 6b9917f08a94bd1818be563faa75e4b05662f2a3..2d6bfbfd9bd53fd57b271bdf5582d9f6a25fb1ed 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1087,9 +1087,6 @@ class Isolate {
     return id;
   }
 
-  // Get (and lazily initialize) the registry for per-isolate symbols.
-  Handle<JSObject> GetSymbolRegistry();
-
   void AddCallCompletedCallback(CallCompletedCallback callback);
   void RemoveCallCompletedCallback(CallCompletedCallback callback);
   void FireCallCompletedCallback();
@@ -1117,6 +1114,9 @@ class Isolate {
   bool IsRunningMicrotasks() const { return is_running_microtasks_; }
   int GetNextDebugMicrotaskId() { return debug_microtask_count_++; }
 
+  Handle<Symbol> SymbolFor(Heap::RootListIndex dictionary_index,
+                           Handle<String> name, bool private_symbol);
+
   void SetUseCounterCallback(v8::Isolate::UseCounterCallback callback);
   void CountUsage(v8::Isolate::UseCounterFeature feature);
 
@@ -1187,8 +1187,6 @@ class Isolate {
  private:
   friend struct GlobalState;
   friend struct InitializeGlobalState;
-  Handle<JSObject> SetUpSubregistry(Handle<JSObject> registry, Handle<Map> map,
-                                    const char* name);
 
   // These fields are accessed through the API, offsets must be kept in sync
   // with v8::internal::Internals (in include/v8.h) constants. This is also