Fix Native::Object#is_a? semantics

meh · meh · commit d21fba043e27 · 2014-02-04T00:32:40.000+01:00
diff --git a/stdlib/native.rb b/stdlib/native.rb
@@ -229,13 +229,13 @@ def nil?
   end
 
   def is_a?(klass)
-    klass == Native
+    `$opal.is_a(self, klass)`
   end
 
   alias kind_of? is_a?
 
   def instance_of?(klass)
-    klass == Native
+    `self._klass === klass`
   end
 
   def class
