Ie siblings

Behold, and be afraid. Again.

With this patch, tests pass in IE11. Further version testing to come, but this makes us work in new versions of all major browsers.

* I removed a test for `camelCasing` being preserved. I think the test is at fault and not the code, but regardless the camel case features are only required for svg. Will bring back a test with a proper DOM element when SVG comes back.
* IE11's deep `cloneNode` has a bad behavior. It destroys blank text nodes. HTMLBars uses blank text nodes pretty liberally to provide morph context. In this PR, I have written `repairClonedNode` dom helper that brings back the missing text nodes.

In order to send the `repairClonedNode` opcode on hydration before firing any child opcodes, we must have the AST build the blank node list when walking the AST. This is sure to be controversial :-p but hopefully less so than adding the text nodes one-at-a-time.

(can squash, trying to keep the commits small so the story is still clear)