Make 'where' lazy.

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 124 matching lines @@
   Iterable mappedBy(f(element)) {
     return new MappedIterable<int, dynamic>(this, f);
   }
 
   Dynamic reduce(Dynamic initialValue,
                  Dynamic combine(Dynamic initialValue, element)) {
     return Collections.reduce(this, initialValue, combine);
   }
 
   Collection where(bool f(element)) {
-    return Collections.where(this, new List(), f);
+    return new WhereIterable<int>(this, f);
   }
 
   bool every(bool f(element)) {
     return Collections.every(this, f);
   }
 
   bool some(bool f(element)) {
     return Collections.some(this, f);
   }
 
@@ skipping 2246 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;
 }