Move Iterable implementation to collection.

sdk/lib/_internal/compiler/implementation/scanner/string_scanner.dart

 // Copyright (c) 2011, 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.
 
 part of scanner;
 
 /**
  * Scanner that reads from a String and creates tokens that points to
  * substrings.
  */
@@ skipping 35 matching lines @@
     // over correct code. By inserting an additional error token in
     // the stream, we can keep ignoring endGroup tokens.
     Token next =
         new StringToken.fromSource(BAD_INPUT_INFO, error, begin.charOffset);
     begin.endGroup = close;
     close.next = next;
     next.next = begin.next;
   }
 }
 
-class SubstringWrapper extends Iterable<int> implements SourceString {
+class SubstringWrapper extends IterableBase<int> implements SourceString {
   final String internalString;
   final int begin;
   final int end;
   int cashedHash = 0;
   String cachedSubString;
 
   SubstringWrapper(String this.internalString,
                    int this.begin, int this.end);
 
   int get hashCode {
@@ skipping 30 matching lines @@
     assert(0 <= terminal);
     assert(initial + terminal <= internalString.length);
     return new SubstringWrapper(internalString,
                                 begin + initial, end - terminal);
   }
 
   bool get isEmpty => begin == end;
 
   bool isPrivate() => !isEmpty && internalString.codeUnitAt(begin) == $_;
 }