dart2js: remove JS_OBJECT_CLASS_NAME and JS_NULL_CLASS_NAME from foreign

pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart

Index: pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
diff --git a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
index 941d64dc244c32518b622804d651b4e810144358..3505c861f79f116c11b7b62ddc3e3e9496344b84 100644
--- a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
+++ b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
@@ -1656,10 +1656,7 @@ class SimpleTypeInferrerVisitor<T>
           compiler.enqueuer.resolution.nativeEnqueuer.getNativeBehaviorOf(node);
       sideEffects.add(nativeBehavior.sideEffects);
       return inferrer.typeOfNativeBehavior(nativeBehavior);
-    } else if (name == 'JS_NULL_CLASS_NAME'
-               || name == 'JS_OBJECT_CLASS_NAME'
-               || name == 'JS_OPERATOR_AS_PREFIX'
-               || name == 'JS_STRING_CONCAT') {
+    } else if (name == 'JS_OPERATOR_AS_PREFIX' || name == 'JS_STRING_CONCAT') {
       return types.stringType;
     } else {
       sideEffects.setAllSideEffects();