Typing -->
on the beginning of a line of code in JavaScript seems to comment it. But looks like there isn't almost no info available about this.
What i found so far is a v8 (test)[https://github.com/crosswalk-project/v8-crosswalk/blob/master/test/webkit/parser-xml-close-comment.js] that does test for this feature. So it looks like it is done intentionally.
Looks like v8 and Firefox's JS engine do both parse this correctly. MuJS does throw an syntax error
SyntaxError: test.js:2: unexpected token in expression: '>'