Adds native JsType tests for defenders.

Change-Id: I141ab0ccdf094a936461b070c99a0e1e85e95da7

dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java

diff --git a/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java b/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
index b2e4ca3..8c42740 100644
--- a/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
+++ b/dev/core/test/com/google/gwt/dev/jjs/impl/JsInteropRestrictionCheckerTest.java
@@ -1355,6 +1355,23 @@
         "Line 6: Native JsType ''EntryPoint.Buggy'' can only extend native JsType interfaces.");
   }
 
+  public void testNativeJsTypeInterfaceDefenderMethodsFails() throws Exception {
+    addSnippetImport("jsinterop.annotations.JsType");
+    addSnippetImport("jsinterop.annotations.JsOverlay");
+    addSnippetClassDecl(
+        "@JsType(isNative=true) public interface Buggy {",
+        "  default void someMethod(){}",
+        "  @JsOverlay",
+        "  default void someOverlayMethod(){}",
+        "}");
+
+    assertBuggyFails(
+        "Line 6: Native JsType method 'void EntryPoint.Buggy.someMethod()' should be native "
+            + "or abstract.",
+        "Line 8: JsOverlay method 'void EntryPoint.Buggy.someOverlayMethod()' cannot be "
+            + "non-final nor native.");
+  }
+
   public void testJsOverlayOnNativeJsTypeMemberSucceeds() throws Exception {
     addSnippetImport("jsinterop.annotations.JsType");
     addSnippetImport("jsinterop.annotations.JsOverlay");