Implement reflection on annotations of parameters.

sdk/lib/_internal/compiler/implementation/js/builder.dart

Index: sdk/lib/_internal/compiler/implementation/js/builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js/builder.dart b/sdk/lib/_internal/compiler/implementation/js/builder.dart
index 8958b50fcc2f3b6cc5a191684b8fd5b5764d60d4..634444719f15e4714942864742351fc7126cd89b 100644
--- a/sdk/lib/_internal/compiler/implementation/js/builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/js/builder.dart
@@ -126,16 +126,12 @@ class JsBuilder {
       }
       return new ObjectInitializer([]);
     } else if (expression is List) {
-      var values = new List<ArrayElement>(expression.length);
-      int index = 0;
-      for (var entry in expression) {
-        values[index] = new ArrayElement(index, toExpression(entry));
-        index++;
-      }
+      var values = new List<ArrayElement>.generate(expression.length,
+          (index) => new ArrayElement(index, toExpression(expression[index])));
       return new ArrayInitializer(values.length, values);
     } else {
       throw new ArgumentError('expression should be an Expression, '
-                              'a String, a num, a bool, or a Map');
+                              'a String, a num, a bool, a Map, or a List;');
     }
   }