ZJIT: Remove unneeded omission for optional param test

Author: st0012

test/ruby/test_zjit.rb

@@ -487,7 +487,6 @@ def test
   end
 
   def test_invokebuiltin
-    omit 'Test fails at the moment due to not handling optional parameters'
     assert_compiles '["."]', %q{
       def test = Dir.glob(".")
       test