fix(compiler): properly associate source spans for implicitly closed elements

[JoostK]

HTML is very lenient when it comes to closing elements, so Angular's parser has
rules that specify which elements are implicitly closed when closing a tag.
The parser keeps track of the nesting of tag names using a stack and parsing
a closing tag will pop as many elements off the stack as possible, provided
that the elements can be implicitly closed.

For example, consider the following templates:

• <div><br></div>, the <br> is implicitly closed when parsing </div>,
    because <br> is a void element.
• <div><p></div>, the <p> is implicitly closed when parsing </div>,
    as <p> is allowed to be closed by the closing of its parent element.
• <ul><li>A <li>B</ul>, the first <li> is implicitly closed when parsing
    the second <li>, whereas the second <li> would be implicitly closed when
    parsing the </ul>.

In all the cases above the parsed structure would be correct, however the source
span of the closing </div> would incorrectly be assigned to the element that
is implicitly closed. The problem was that closing an element would associate
the source span with the element at the top of the stack, however this may not
be the element that is actually being closed if some elements would be
implicitly closed.

This commit fixes the issue by assigning the end source span with the element
on the stack that is actually being closed. Any implicitly closed elements that
are popped off the stack will not be assigned an end source span, as the
implicit closing implies that no ending element is present.

Note that there is a difference between self-closed elements such as <input/>
and implicitly closed elements such as <input>. The former does have an end
source span (identical to its start source span) whereas the latter does not.

Fixes #36118
Resolves FW-2004

[petebacondarwin]

Really nice and clean. Great commit message! And very nice way of testing.
A couple of nits, 'tis all! Thanks for taking this one.

[AndrewKushnir]

Presubmit

[sonukapoor]

Really nice and clean. Great commit message! And very nice way of testing.

Very much agreed 💯

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}