update for ejs after the big ES6 update on kangax's table
Merge pull request #159 from toshok/ejs-update

Update for ejs after the big ES6 update on kangax's table
ES6: reinforced the let test

Now, let functionality requires:
* Functional outside "extended mode" and the
"application/javascript;version=1.8" script tag type.
* Temporal dead zone (fixes #131).
* No hoisting out of blocks and for-loop heads.
* For-loops create fresh bindings.

I'm not able to check if EchoJS or IE11 actually pass this reinforced
test, but it seems Traceur doesn't (its 'experimental' output fails the
"qux" check as of today).
Fixed bug in double-let test

Double-lets are actually syntax errors, which can't be caught unless
they are eval()-ed at runtime.