Fast JNI support.

Use a modifier to signal a native method is a fast JNI method. If the
modifier is set then don't perform runnable transitions.

Change-Id: I7835b4d837bfdd1cb8e2d54b919c0d5e6cf90499
diff --git a/runtime/mirror/class.cc b/runtime/mirror/class.cc
index 2b0b1e1..319ca4a 100644
--- a/runtime/mirror/class.cc
+++ b/runtime/mirror/class.cc
@@ -661,7 +661,9 @@
     for (int32_t index = 0, end = methods->GetLength(); index < end; ++index) {
       mirror::ArtMethod* method = methods->GetWithoutChecks(index);
       DCHECK(method != NULL);
-      method->SetPreverified();
+      if (!method->IsNative() && !method->IsAbstract()) {
+        method->SetPreverified();
+      }
     }
   }
 }