Officially drop IE9-10 support, pull out our hacks (#2296)

- I also fixed a bunch of related comments
- I had to polyfill `requestAnimationFrame` for Node
- Drive-by: run `eslint . --fix`
- Drive-by: update transpiling info in CONTRIBUTING.md
- Drive-by: we aren't the only ones going semicolon-free

tests/test-api.js

@@ -24,7 +24,7 @@ o.spec("api", function() {
 		o("works", function() {
 			o(typeof m.version).equals("string")
 			o(m.version.indexOf(".") > -1).equals(true)
-			o(/\d/.test(m.version)).equals(true)
+			o((/\d/).test(m.version)).equals(true)
 		})
 	})
 	o.spec("m.trust", function() {