JS backend: fixed ability to declare custom name for native properties and function parameters.

#KT-3643 fixed

js/js.tests/test/org/jetbrains/k2js/test/semantics/NativeInteropTest.java

@@ -88,4 +88,8 @@ public final class NativeInteropTest extends SingleFileTranslationTest {
     public void testKt2323() throws Exception {
         fooBoxTest();
     }
+
+    public void testNativePropertyWithCustomName() throws Exception {
+        checkFooBoxIsOk();
+    }
 }

js/js.tests/test/org/jetbrains/k2js/test/semantics/PropertyAccessTest.java

@@ -94,6 +94,10 @@ public final class PropertyAccessTest extends SingleFileTranslationTest {
         fooBoxTest();
     }
 
+    public void testNativePropertiesNameClashes() throws Exception {
+        checkFooBoxIsOk();
+    }
+
     @Override
     @NotNull
     protected List<String> additionalJSFiles(@NotNull EcmaVersion ecmaVersion) {