testsuite: Tests for #6458. Closes #6458
std/extra: changing XXX to FIXME; cleanup

* Get rid of by-value-self workarounds; it works now
* Remove type annotations, they're not needed anymore
* Move http module to extra
extra: change alloc to take &mut self, as per XXX comment
extra: change XXX to FIXME and elaborate on comments
Testsuite: Test for #7013. Closes #7013
auto merge of #8570 : catamorphism/rust/2013-08-16-rollup, r=catamorphism

Nothing arguable here, as far as I can tell.