Remove deprecated mappedBy.

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.transferable(int length) {
@@ skipping 215 matching lines @@
     var len = this.length;
     for (var i = 0; i < len; i++) {
       f(this[i]);
     }
   }
 
   Iterable map(f(int element)) {
     return IterableMixinWorkaround.mapList(this, f);
   }
 
-  List mappedBy(f(int element)) {
-    return IterableMixinWorkaround.mappedByList(this, f);
-  }
-
   String join([String separator]) {
     return IterableMixinWorkaround.join(this, separator);
   }
 
   dynamic reduce(dynamic initialValue,
                  dynamic combine(dynamic initialValue, element)) {
     return IterableMixinWorkaround.reduce(this, initialValue, combine);
   }
 
   Collection where(bool f(int element)) {
@@ skipping 2427 matching lines @@
   ByteArray asByteArray([int start = 0, int length]) {
     if (length == null) {
       length = this.lengthInBytes();
     }
     _rangeCheck(this.length, start, length);
     return _array.subByteArray(_offset + start, length);
   }
 
   static const int _BYTES_PER_ELEMENT = 8;
 }