Added back helper file accidentally deleted during test block 219 migration.

tests/lib_2/mirrors/delegate_library_test.dart

Index: tests/lib_2/mirrors/delegate_library_test.dart
diff --git a/tests/lib_strong/mirrors/delegate_library_test.dart b/tests/lib_2/mirrors/delegate_library_test.dart
similarity index 93%
rename from tests/lib_strong/mirrors/delegate_library_test.dart
rename to tests/lib_2/mirrors/delegate_library_test.dart
index f441a7b16bd95a8d08c7154eb8f4989da939132c..a4cf43224d586b179193f6b825aae48a47a81d58 100644
--- a/tests/lib_strong/mirrors/delegate_library_test.dart
+++ b/tests/lib_2/mirrors/delegate_library_test.dart
@@ -14,7 +14,6 @@ methodWithOpt(a, [b, c = 'C']) => "$a-$b-$c";
 get getter => 'g';
 set setter(x) {
   field = x * 2;
-  return 'unobservable value';
 }
 
 var field;
@@ -26,7 +25,7 @@ class Proxy {
 }
 
 main() {
-  var proxy = new Proxy(reflectClass(Proxy).owner);
+  dynamic proxy = new Proxy(reflectClass(Proxy).owner);
   var result;
 
   Expect.equals('X-Y-Z', proxy.method('X', 'Y', 'Z'));