Safe calls work for native properties

#KT-2209 fixed

js/js.translator/testFiles/native/cases/kt2209.kt

@@ -0,0 +1,24 @@
+package foo
+
+native
+trait Chrome {
+  val extension:Extension
+}
+
+native
+trait Extension {
+  val lastError:LastError?
+}
+
+native
+trait LastError {
+  val message:String
+}
+
+native
+val chrome:Chrome = noImpl
+
+fun box() : Boolean {
+    val lastError = chrome.extension.lastError?.message
+    return lastError == null
+}

js/js.translator/testFiles/native/native/kt2209.js

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+var chrome = {extension: {lastError:null}}