Fix identation textarea (related to issue #117)

[benjamin-dreux]

For the moment, add a failing test for view with indentation that do not indent for textarea element.
I intent to propose a fix also for #117 with this same PR.

But let's agree on the test required first

[benjamin-dreux]

After playing with
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/textarea I also noticed that in a textarea the first line return is not taken into consideration, but the one before the closing tag is.

So we ended with something that could look weird but is indented as much as possible as long as it does not affect the content of the textarea itself.

I'm not quite certain if this introduce regression on text inside an element diffrent from textarea