[opal-0.9] Fix ruby specs

Shim `console.warn` trigger by “Object.freezing non support” added in opal 0.9

Author: zetachang

spec/reactive-ruby/component_loader_spec.rb

@@ -6,6 +6,9 @@
     var global = global || this;
     var self = self || this;
     var window = window || this;
+    var console = {
+      warn: function(s) {  }
+    };
   JS
 
   let(:js) { ::Rails.application.assets['components'].to_s }