Fix implementations of Match too, to use "input", not "str".

runtime/lib/regexp_patch.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 RegExp {
   /* patch */ factory RegExp(String source,
                              {bool multiLine: false,
                               bool caseSensitive: true}) {
     return new _JSSyntaxRegExp(source,
                                multiLine: multiLine,
                                caseSensitive: caseSensitive);
   }
 }
 
 class _JSRegExpMatch implements Match {
-  _JSRegExpMatch(this._regexp, this.str, this._match);
+  _JSRegExpMatch(this._regexp, this.input, this._match);
 
   int get start => _start(0);
   int get end => _end(0);
 
   int _start(int groupIdx) {
     return _match[(groupIdx * _MATCH_PAIR)];
   }
 
   int _end(int groupIdx) {
     return _match[(groupIdx * _MATCH_PAIR) + 1];
   }
 
   String group(int groupIdx) {
     if (groupIdx < 0 || groupIdx > _regexp._groupCount) {
       throw new RangeError.value(groupIdx);
     }
     int startIndex = _start(groupIdx);
     int endIndex = _end(groupIdx);
     if (startIndex == -1) {
       assert(endIndex == -1);
       return null;
     }
-    return str._substringUnchecked(startIndex, endIndex);
+    return input._substringUnchecked(startIndex, endIndex);
   }
 
   String operator [](int groupIdx) {
     return this.group(groupIdx);
   }
 
   List<String> groups(List<int> groupsSpec) {
     var groupsList = new List<String>(groupsSpec.length);
     for (int i = 0; i < groupsSpec.length; i++) {
       groupsList[i] = group(groupsSpec[i]);
     }
     return groupsList;
   }
 
   int get groupCount => _regexp._groupCount;
 
   Pattern get pattern => _regexp;
 
+  // TODO(12843): Remove when grace period is over.
+  String get str => input;
+
   final RegExp _regexp;
-  final String str;
+  final String input;
   final List<int> _match;
   static const int _MATCH_PAIR = 2;
 }
 
 
 class _JSSyntaxRegExp implements RegExp {
   factory _JSSyntaxRegExp(
       String pattern,
       {bool multiLine: false,
        bool caseSensitive: true}) native "JSSyntaxRegExp_factory";
@@ skipping 84 matching lines @@
     var match = _re._ExecuteMatch(_str, nextIndex);
     if (match == null) {
       _current = null;
       _re = null;
       return false;
     }
     _current = new _JSRegExpMatch(_re, _str, match);
     return true;
   }
 }