1. in pkg/template_binding/test/custom_element_bindings_test.dart, revert this patch: https://codereview.chromium.org/33173004

• AttributeMapWrapper _attributes;
• AttributeMapWrapper<String, String> _attributes;

1. run ./tools/test.py -m release -r drt --checked pkg/template_binding/test/custom_element_bindings
2. test will fail with http://127.0.0.1:35051/root_build/generated_compilations/dart2js-checked/pkg_template_binding_test_custom_element_bindings_test/test.js:3819:
   Uncaught type 'AttributeMapWrapper' is not a subtype of type 'AttributeMapWrapper'

which is strange. IIRC, plain AttributeMapWrapper should mean AttributeMapWrapper<dynamic, dynamic> which is assignable to AttributeMapWrapper<String, String>