Move Iterable implementation to collection.

sdk/lib/utf/utf8.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.
 
 part of dart.utf;
 
 const int _UTF8_ONE_BYTE_MAX = 0x7f;
 const int _UTF8_TWO_BYTE_MAX = 0x7ff;
 const int _UTF8_THREE_BYTE_MAX = 0xffff;
 
@@ skipping 113 matching lines @@
       replacementCodepoint).decodeRest();
 }
 
 /**
  * Return type of [decodeUtf8AsIterable] and variants. The Iterable type
  * provides an iterator on demand and the iterator will only translate bytes
  * as requested by the user of the iterator. (Note: results are not cached.)
  */
 // TODO(floitsch): Consider removing the extend and switch to implements since
 // that's cheaper to allocate.
-class IterableUtf8Decoder extends Iterable<int> {
+class IterableUtf8Decoder extends IterableBase<int> {
   final List<int> bytes;
   final int offset;
   final int length;
   final int replacementCodepoint;
 
   IterableUtf8Decoder(this.bytes, [this.offset = 0, this.length = null,
       this.replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]);
 
   Utf8Decoder get iterator =>
       new Utf8Decoder(bytes, offset, length, replacementCodepoint);
@@ skipping 121 matching lines @@
       return true;
     } else if (replacementCodepoint != null) {
       _current = replacementCodepoint;
       return true;
     } else {
       throw new ArgumentError(
           "Invalid UTF8 at ${utf8EncodedBytesIterator.position - j}");
     }
   }
 }