Support for native DOM4 mutation methods

[rvagg]

DOM4 includes mutation methods: append(), prepend(), before(), after(), replace(), and remove(), potentially taking a variety of argument types (nodes, strings). Would be great to (1) benchmark and (2) leverage these methods in Bonzo (when they are available!).

remove() is already in WebKit with the rest to come.

/ht @paulirish @ https://plus.google.com/u/0/113127438179392830442/posts/KLfpJKLDEsv

[ded]

now going thru some old ones... these new methods should definitely get included! i imagine they will bench much faster