Address Ivan's comments.

runtime/lib/byte_array.dart

 // Copyright (c) 2012, 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 class Int8List {
   /* patch */ factory Int8List(int length) {
     return new _Int8Array(length);
   }
 
   /* patch */ factory Int8List.view(ByteArray array,
@@ skipping 1598 matching lines @@
   int setFloat64(int byteOffset, double value) {
     return _array._setFloat64(_offset + byteOffset, value);
   }
 
   final _ByteArrayBase _array;
   final int _offset;
   final int _length;
 }
 
 
+// TODO(floitsch): extending the collection adds extra cost (because of type
+// parameters). Consider copying the functions from Collection into this class
+// and just implementing Collection<int>.
 class _ByteArrayViewBase extends Collection<int> {
   num operator[](int index);
 
   // Methods implementing the Collection interface.
 
   void forEach(void f(element)) {
     var len = this.length;
     for (var i = 0; i < len; i++) {
       f(this[i]);
     }
@@ skipping 781 matching lines @@
     }
     _rangeCheck(this.length, start, length);
     return _array.subByteArray(_offset + start, length);
   }
 
   static const int _BYTES_PER_ELEMENT = 8;
   final ByteArray _array;
   final int _offset;
   final int _length;
 }