Various semantic checks on formal parameters.

pkg/front_end/lib/src/fasta/source/stack_listener.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.stack_listener;
 
 import '../fasta_codes.dart' show FastaMessage;
 
 import '../parser.dart' show Listener, MemberKind;
 
@@ skipping 66 matching lines @@
   }
 
   Object peek() => stack.last;
 
   Object pop() => stack.pop();
 
   Object popIfNotNull(Object value) {
     return value == null ? null : pop();
   }
 
-  List popList(int n) {
+  List popList(int n, [List list]) {
     if (n == 0) return null;
-    return stack.popList(n);
+    return stack.popList(n, list);
   }
 
   void debugEvent(String name) {
     // printEvent(name);
   }
 
   void printEvent(String name) {
     for (Object o in stack.values) {
       String s = "  $o";
       int index = s.indexOf("\n");
@@ skipping 191 matching lines @@
     }
   }
 
   Object pop() {
     assert(arrayLength > 0);
     final Object value = array[--arrayLength];
     array[arrayLength] = null;
     return value is NullValue ? null : value;
   }
 
-  List popList(int count) {
+  List popList(int count, List list) {
     assert(arrayLength >= count);
 
     final table = array;
     final length = arrayLength;
 
-    final tailList = new List.filled(count, null, growable: true);
+    final tailList = list ?? new List.filled(count, null, growable: true);
     final startIndex = length - count;
     for (int i = 0; i < count; i++) {
       final value = table[startIndex + i];
       tailList[i] = value is NullValue ? null : value;
     }
     arrayLength -= count;
 
     return tailList;
   }
 
   List get values {
     final List list = new List(arrayLength);
     list.setRange(0, arrayLength, array);
     return list;
   }
 
   void _grow() {
     final List newTable = new List(array.length * 2);
     newTable.setRange(0, array.length, array, 0);
     array = newTable;
   }
 }