Fix: Latest HTML position trumps latest entry

[ftes]

Looking at #137 I realised we probably have a bug (already prior to #137).

Todo

• Add failing test
• Fix

Given

<label>Email duplicate 1<input id="email-duplicate-1" name="email" /></label>
<label>Email duplicate 2<input id="email-duplicate-2" name="email" /></label>

|> fill_in("Email duplicate 2", with: "Latest HTML position")
|> fill_in("Email duplicate 1", with: "Latest fill_in")

Expected

# POST email=Latest fill_in&email=Latest HTML position
params = %{"email" => "Latest HTML position"}

Actual

params = %{"email" => "Latest fill_in"}

Background

list of all the submittable elements whose form owner is form, in tree order
https://www.w3.org/TR/2011/WD-html5-20110525/association-of-controls-and-forms.html#constructing-form-data-set

[ftes]

Unrelated, but a recurring thought:

Adding a JS driver will help prevent some of these HTML-semantics-bugs.
Because running the existing tests with an actual browser shows that at least for those cases we are HTML-spec-conformant.

Along the same lines I've found a few edge case bugs while working on #136 and #74 because existing tests were unexpectedly failing.

[ftes]

I'll close this for now. Not too common a problem, no easy fix.
But maybe something for back of mind.