We can reset `<input type=text>` fields! I wish I could've done something with checkboxes, but unfortunately, that's it for now.
In addition to that, this PR implements `HTMLInputAttribute.defaultValue`, updates wpt-test to expect passing tests as a result of that implementation, and fixes an index error crash with text inputs.
edit: also includes an html example where one may lazily watch form resets in action: ` tests/html/form_reset_handsfree.html`
Source-Repo: https://github.com/servo/servo
Source-Revision: 5951056973fc0e08e70224214740a274ca8ef20f
Fixes#3918
Can be tested in `tests/html/textarea.html`. Also implemented some content reflecting IDL attributes for HTMLTextAreaElement while I was in there.
There are some major problems with TextInput when Multiple is enabled that I haven't addressed here, but I'm prepared to open up a follow-up issue.
Source-Repo: https://github.com/servo/servo
Source-Revision: a369dcfa01f5ad7634469f3a3b652d7f650129a0
