Bug 844426 - limit to ES5 syntax; get rid of generators, fix tests

Test fixes are due to TextEncoder not supporting US-ASCII on Firefox nightly.
Merge pull request #2 from asutherland/es5-syntax-only

Bug 844426 - limit to ES5 syntax; get rid of generators, fix tests
Merge pull request #4 from mozilla-b2g/master

Merge mozilla-b2g changes into mozsquib repo