docs(guide/Animations): fix punctuation

Closes #10398
docs(CHANGELOG.md): better group changes in 1.3.6

Closes #10392
fix($http): don't convert FormData objects to JSON

This won't enable FormData uploads in itself, as the Content-Type is automatically set to application/json.

Closes #10373
refactor($http): avoid re-creating execHeaders function

The execHeaders function was being re-defined inside mergeHeaders
function. Additionally it was mutating its arguments.

Closes #10359
chore($$raf) remove moz prefix for requestAnimationFrame

This drops support for Firefox 22 and older.

The moz-prefix is still supported, but there is an effort to drop it eventually:
https://bugzilla.mozilla.org/show_bug.cgi?id=909154

Closes #9577