add test for 5 lines

Author: tenderlove

test/prism/errors_test.rb

@@ -38,6 +38,9 @@ def test_newline_preceding_eof
 
       err = Prism.parse("foo(\n").errors.first
       assert_equal 1, err.location.start_line
+
+      err = Prism.parse("foo(\n\n\n\n\n").errors.first
+      assert_equal 5, err.location.start_line
     end
 
     def test_embdoc_ending