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
chore(travis): run the build twice (BS and SL)

Temporarily run the each job twice:
- using BrowserStack
- using SauceLabs
docs(guide/Forms): added link to input type "date"

Closes #10415
fix($http): only parse as JSON when opening/closing brackets match

Previously, due to weak JSON-detecting RegExp, string like `[...}` and
`{...]` would be considered JSON (even if they obviously aren't) and an
expection would be thrown while trying to parse them.

This commit makes sure the opening and closing brackets match. This
doesn't completely eliminate false positives (e.g. `[]{}[]`), but does
help reduce them.

Closes #10349