Delete polymer from the Dart repo

pkg/polymer/test/mirror_loader_4.dart

Index: pkg/polymer/test/mirror_loader_4.dart
diff --git a/pkg/polymer/test/mirror_loader_4.dart b/pkg/polymer/test/mirror_loader_4.dart
deleted file mode 100644
index 11aa763f7ac9e7e6d858afda2aa845150c3ea80c..0000000000000000000000000000000000000000
--- a/pkg/polymer/test/mirror_loader_4.dart
+++ /dev/null
@@ -1,20 +0,0 @@
-library mirror_loader_test4;
-
-import 'package:polymer/polymer.dart';
-
-@CustomTag('x-a')
-class XA extends PolymerElement {
-  final String x = "a";
-  XA.created() : super.created();
-}
-
-// The next classes are here as a regression test for darbug.com/17929. Our
-// loader was incorrectly trying to retrieve the reflectiveType of these
-// classes.
-class Foo<T> {}
-
-@CustomTag('x-b')
-class XB<T> extends PolymerElement {
-  final String x = "a";
-  XB.created() : super.created();
-}