PreParsing inner funcs: Do fewer variable name lookups.

src/ast/scopes.h

Index: src/ast/scopes.h
diff --git a/src/ast/scopes.h b/src/ast/scopes.h
index 5956b6f8a650b57a56764769924ceae3ab5c5201..ac8eb1a75436e502971c02728fd8329d2e6d5212 100644
--- a/src/ast/scopes.h
+++ b/src/ast/scopes.h
@@ -34,8 +34,8 @@ class VariableMap: public ZoneHashMap {
                     MaybeAssignedFlag maybe_assigned_flag = kNotAssigned,
                     bool* added = nullptr);
 
-  // Records that "name" exists but doesn't create a Variable. Useful for
-  // preparsing.
+  // Records that "name" exists (if not recorded yet) but doesn't create a
+  // Variable. Useful for preparsing.
   void DeclareName(Zone* zone, const AstRawString* name);
 
   Variable* Lookup(const AstRawString* name);