Split NewScope into NewScope and NewScopeWithParent

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index 11416d508da93625d5b1fa9fffa1cf1bd9b3d49a..57e37c4fdf6617de73f69ca1c53f498858ec0985 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -619,7 +619,14 @@ class ParserBase : public Traits {
     return new (zone()) Scope(zone(), nullptr, SCRIPT_SCOPE, kNormalFunction);
   }
 
-  Scope* NewScope(Scope* parent, ScopeType scope_type) {
+  Scope* NewScope(ScopeType scope_type) {
+    return NewScopeWithParent(scope(), scope_type);
+  }
+
+  // This constructor should only be used when absolutely necessary. Most scopes
+  // should automatically use scope() as parent, and be fine with
+  // NewScope(ScopeType) above.
+  Scope* NewScopeWithParent(Scope* parent, ScopeType scope_type) {
     // Must always use the specific constructors for the blacklisted scope
     // types.
     DCHECK_NE(FUNCTION_SCOPE, scope_type);