Remove deprecated mappedBy.

Committed: https://code.google.com/p/dart/source/detail?r=18575
Reverted: http://code.google.com/p/dart/source/detail?r=18576

Review URL: https://codereview.chromium.org//12212213

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@18579 260f80e4-7a28-3924-810f-c04153c831b5

pkg/http/lib/src/byte_stream.dart

@@ -35,5 +35,5 @@ class ByteStream extends StreamView<List<int>> {
       toBytes().then((bytes) => decodeString(bytes, encoding));
 
   Stream<String> toStringStream([Encoding encoding=Encoding.UTF_8]) =>
-      wrapStream(mappedBy((bytes) => decodeString(bytes, encoding)));
+      wrapStream(map((bytes) => decodeString(bytes, encoding)));
 }