Compile time error if name is used before variable is declared

runtime/lib/typed_data.dart

 // Copyright (c) 2013, 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.
 
 // patch classes for Int8List ..... Float64List and ByteData implementations.
 
 patch class Int8List {
   /* patch */ factory Int8List(int length) {
     return new _Int8Array(length);
   }
@@ skipping 493 matching lines @@
 
   Set toSet() {
     return new Set.from(this);
   }
 
   Map<int, num> asMap() {
     return IterableMixinWorkaround.asMapList(this);
   }
 
   List sublist(int start, [int end]) {
-    if (end == null) end = length;
+    if (end == null) end = this.length;
     int length = end - start;
     _rangeCheck(this.length, start, length);
     List result = _createList(length);
     result.setRange(0, length, this, start);
     return result;
   }
 
   Iterable getRange(int start, [int end]) {
     return IterableMixinWorkaround.getRangeList(this, start, end);
   }
@@ skipping 2821 matching lines @@
     return value;
   }
   return object;
 }
 
 
 void _throwRangeError(int index, int length) {
   String message = "$index must be in the range [0..$length)";
   throw new RangeError(message);
 }