All strong mode cleaning of dart2js.

pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart

Index: pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
index 442aa31893289defe6200a16c0feb68f545f10fb..fa00f1ed5c9401e66ffb859ad15f6ddcd2e0bcae 100644
--- a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
@@ -177,8 +177,14 @@ class RuntimeTypeGenerator {
       }
     }
 
-    _generateIsTestsOn(classElement, generateIsTest,
-        generateFunctionTypeSignature, generateSubstitution, generateTypeCheck);
+    _generateIsTestsOn(classElement, (Element e) {
+      generateIsTest(e);
+    }, (Element e, ResolutionFunctionType t) {
+      generateFunctionTypeSignature(e, t);
+    },
+        (Element e, {bool emitNull: false}) =>
+            generateSubstitution(e, emitNull: emitNull),
+        generateTypeCheck);
 
     if (classElement == _commonElements.jsJavaScriptFunctionClass) {
       var type = _jsInteropAnalysis.buildJsFunctionType();