Bug 911169

Hi,

I have fixed the bug and pass the test, please have a review.

In local test environment (webmaker-suite/thimble.webmaker.org), I need to update:
friendlycode/vendor/slowparse/slowparse.js, 
views/slowparse/errors.base.html,
locale/en-US/messages.json; 

but here (mozilla/slowparse) I only updated:
slowparse.js, 
spec/errors.base.html (which seems combine the errors.base.html and messages.json in webmaker-suite case?)

Thank you!
xdchen