Add optional start index to Pattern.allMatches.

runtime/lib/string_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 String {
   /* patch */ factory String.fromCharCodes(Iterable<int> charCodes) {
     return _StringBase.createFromCharCodes(charCodes);
   }
 
   /* patch */ factory String.fromCharCode(int charCode) {
@@ skipping 522 matching lines @@
         }
       }
       stringList[i] = s;
     }
     if (isOneByteString) {
       return _OneByteString._concatAll(stringList, totalLength);
     }
     return _concatRangeNative(stringList, 0, stringList.length);
   }
 
-  Iterable<Match> allMatches(String str) {
+  Iterable<Match> allMatches(String string, [int start = 0]) {
     List<Match> result = new List<Match>();
-    int length = str.length;
+    int length = string.length;
     int patternLength = this.length;
-    int startIndex = 0;
+    int startIndex = start;
     while (true) {
-      int position = str.indexOf(this, startIndex);
+      int position = string.indexOf(this, startIndex);
       if (position == -1) {
         break;
       }
-      result.add(new _StringMatch(position, str, this));
+      result.add(new _StringMatch(position, string, this));
       int endIndex = position + patternLength;
       if (endIndex == length) {
         break;
       } else if (position == endIndex) {
         ++startIndex;  // empty match, advance and restart
       } else {
         startIndex = endIndex;
       }
     }
     return result;
@@ skipping 440 matching lines @@
 class _CodeUnits extends Object with ListMixin<int>,
                                      UnmodifiableListMixin<int> {
   /** The string that this is the code units of. */
   String _string;
 
   _CodeUnits(this._string);
 
   int get length => _string.length;
   int operator[](int i) => _string.codeUnitAt(i);
 }