Make JNI work correctly with default methods.

Also adds some tests for JNI and DefaultMethods.

Bug: 27259142
Bug: 24618811

Change-Id: I31222e3e41059d803be1dbb0f40e1144ac4bf457
diff --git a/runtime/class_linker_test.cc b/runtime/class_linker_test.cc
index 5c3029a..488826b 100644
--- a/runtime/class_linker_test.cc
+++ b/runtime/class_linker_test.cc
@@ -263,7 +263,7 @@
     for (ArtMethod& method : klass->GetCopiedMethods(sizeof(void*))) {
       AssertMethod(&method);
       EXPECT_FALSE(method.IsDirect());
-      EXPECT_TRUE(method.MightBeCopied());
+      EXPECT_TRUE(method.IsCopied());
       EXPECT_TRUE(method.GetDeclaringClass()->IsInterface())
           << "declaring class: " << PrettyClass(method.GetDeclaringClass());
       EXPECT_TRUE(method.GetDeclaringClass()->IsAssignableFrom(klass.Get()))