Finish strong mode cleaning of dart2js.

pkg/compiler/lib/src/resolution/no_such_method_resolver.dart

Index: pkg/compiler/lib/src/resolution/no_such_method_resolver.dart
diff --git a/pkg/compiler/lib/src/resolution/no_such_method_resolver.dart b/pkg/compiler/lib/src/resolution/no_such_method_resolver.dart
index 49f3353eff3df74309a00b132805a2af14a81609..5e4955f0fa21f652ef01c46b25548e175251e94a 100644
--- a/pkg/compiler/lib/src/resolution/no_such_method_resolver.dart
+++ b/pkg/compiler/lib/src/resolution/no_such_method_resolver.dart
@@ -51,9 +51,11 @@ class ResolutionNoSuchMethodResolver implements NoSuchMethodResolver {
           arg is Send &&
           arg.argumentsNode == null &&
           arg.receiver == null &&
-          arg.selector is Identifier &&
-          arg.selector.source == param) {
-        return true;
+          arg.selector is Identifier) {
+        Identifier selector = arg.selector;
+        if (selector.source == param) {
+          return true;
+        }
       }
     }
     return false;