Mostly use entities in use.dart

pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart

Index: pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
diff --git a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
index 818f82c4b6e320e2b0b21e34aecd44bccbdf0808..613abf9fb86d7f097dcbeb9d3e85c5fcb7f8fb8c 100644
--- a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
+++ b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
@@ -22,8 +22,8 @@ class CheckedModeHelper {
     JavaScriptBackend backend = compiler.backend;
     // TODO(johnniwinther): Refactor this to avoid looking up directly in the
     // js helper library but instead access helpers directly on backend helpers.
-    return new StaticUse.staticInvoke(
-        backend.helpers.jsHelperLibrary.find(name), callStructure);
+    MethodElement method = backend.helpers.jsHelperLibrary.find(name);
+    return new StaticUse.staticInvoke(method, callStructure);
   }
 
   CallStructure get callStructure => CallStructure.ONE_ARG;