Make all global private symbols own symbols.

src/macros.py

Index: src/macros.py
diff --git a/src/macros.py b/src/macros.py
index 131df878b5d8716db6dca81ad3710610f37cfc56..48a425045c8b3d539bea8bc6eebadd38ab6b713c 100644
--- a/src/macros.py
+++ b/src/macros.py
@@ -170,10 +170,11 @@ macro JSON_NUMBER_TO_STRING(arg) = ((%_IsSmi(%IS_VAR(arg)) || arg - arg == 0) ?
 # Private names.
 # GET_PRIVATE should only be used if the property is known to exists on obj
 # itself (it should really use %GetOwnProperty, but that would be way slower).
-macro GLOBAL_PRIVATE(name) = (%CreateGlobalPrivateSymbol(name));
+macro GLOBAL_PRIVATE(name) = (%CreateGlobalPrivateOwnSymbol(name));
 macro NEW_PRIVATE(name) = (%CreatePrivateSymbol(name));
 macro IS_PRIVATE(sym) = (%SymbolIsPrivate(sym));
 macro HAS_PRIVATE(obj, sym) = (%HasOwnProperty(obj, sym));
+macro HAS_DEFINED_PRIVATE(obj, sym) = (!IS_UNDEFINED(obj[sym]));
 macro GET_PRIVATE(obj, sym) = (obj[sym]);
 macro SET_PRIVATE(obj, sym, val) = (obj[sym] = val);
 macro DELETE_PRIVATE(obj, sym) = (delete obj[sym]);