Skip test_symbol on RubyRhinoRuntime for now as it does not work yet

* Waiting for a decision in rubyjs/therubyrhino#43

Author: eregon

test/test_execjs.rb

@@ -168,6 +168,8 @@ def test_context_call_missing_function
   end
 
   def test_symbol
+    skip 'https://github.com/rubyjs/therubyrhino/issues/43' if ExecJS.runtime.is_a?(ExecJS::RubyRhinoRuntime)
+
     context = ExecJS.compile("function echo(test) { return test; }")
     assert_equal "symbol", context.call("echo", :symbol)
   end