- omitting trailing semi-colon in do-while breaks non-browser parser, e.g. uglify-js 1.x
- trailing semi-colon only breaks IE8 if followed by `else` or `while`
- always use braces in do-while body to workaround 2nd case with no size loss in compression
fixes#1568
for(...; x; ...) if (y) break; → for(...; x&&!y; ...);
similarly for `while` and some combinations (i.e. the `break` appears in the
`else` clause, etc.)
