We must use the original element and not the default implementation element when checking if the co…

frog/tests/leg/src/BuiltinInterceptorTest.dart

Index: frog/tests/leg/src/BuiltinInterceptorTest.dart
===================================================================
--- frog/tests/leg/src/BuiltinInterceptorTest.dart	(revision 6727)
+++ frog/tests/leg/src/BuiltinInterceptorTest.dart	(working copy)
@@ -24,6 +24,12 @@
 }
 """;
 
+final String TEST_FOUR = @"""
+foo() {
+  return new List().add(2);
+}
+""";
+
 main() {
   String generated = compile(TEST_ONE, 'foo');
   Expect.isTrue(generated.contains("return a.length;"));
@@ -33,4 +39,7 @@
 
   generated = compile(TEST_THREE, 'foo');
   Expect.isTrue(generated.contains("return 3;"));
+
+  generated = compile(TEST_FOUR, 'foo');
+  Expect.isTrue(generated.contains("push(2);"));
 }