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..ae902d27e214f7a578ea1db7e7b0843c0507a8a8 100644
--- a/src/ast/scopes.h
+++ b/src/ast/scopes.h
@@ -34,9 +34,9 @@ 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.
-  void DeclareName(Zone* zone, const AstRawString* name);
+  // Records that "name" exists (if not recorded yet) but doesn't create a
+  // Variable. Useful for preparsing.
+  void LookupOrDeclareName(Zone* zone, const AstRawString* name);
 
   Variable* Lookup(const AstRawString* name);
   void Remove(Variable* var);