Tighten OpenHandle's extra checks.

src/api.h

Index: src/api.h
diff --git a/src/api.h b/src/api.h
index 128087c895137c876bd62de869ba022a8d074afa..28aea2da9e5e998c7fd4394e472afff168f015ec 100644
--- a/src/api.h
+++ b/src/api.h
@@ -186,9 +186,9 @@ class RegisteredExtension {
   V(Script, JSFunction)                        \
   V(UnboundScript, SharedFunctionInfo)         \
   V(Function, JSFunction)                      \
-  V(Message, JSObject)                         \
+  V(Message, JSMessageObject)                  \
   V(Context, Context)                          \
-  V(External, Foreign)                         \
+  V(External, Object)                          \
   V(StackTrace, JSArray)                       \
   V(StackFrame, JSObject)                      \
   V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
@@ -393,8 +393,8 @@ MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
     const v8::From* that, bool allow_empty_handle) {                        \
     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
     EXTRA_CHECK(that == NULL ||                                             \
-        !(*reinterpret_cast<v8::internal::To**>(                            \
-            const_cast<v8::From*>(that)))->IsFailure());                    \
+        (*reinterpret_cast<v8::internal::Object**>(                         \
+            const_cast<v8::From*>(that)))->Is##To());                       \
     return v8::internal::Handle<v8::internal::To>(                          \
         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
   }