Bug 1631083 [wpt PR 23072] - Fix customized built-in element construc…

…tor behavior, a=testonly

Automatic update from web-platform-tests
Fix customized built-in element constructor behavior

This CL implements two changes:
 1. It fixes the implementation to better match the spec for the
    "create an element for the token" [1] algorithm. Prior to this CL,
    step 7 of that algorithm was skipping directly to step 6 of the
    "create an element" [2] algorithm, skipping over step 5 for
    customized built-in elements. This is now fixed. This case is
    illustrated by the issue and example at [3] and [4]. This becomes
    the first test in customized-built-in-constructor-exceptions.html.

 2. It updates the comments to match the new behavior discussed in [3]
    and the [5] spec PR, which changes the return value in the case
    that a customized built-in element constructor throws an exception.
    With the change above, that is actually already the behavior. So
    this is just a comment change. Two new tests are added to
    customized-built-in-constructor-exceptions.html.

[1] https://html.spec.whatwg.org/multipage/parsing.html#create-an-element-for-the-token
[2] https://dom.spec.whatwg.org/#concept-create-element
[3] whatwg/html#5084
[4] https://crbug.com/1024866
[5] whatwg/dom#797

Bug: 1071059, 1024866
Change-Id: I814c81991eb5e83501304bcb3d2da476743aef52
Cq-Do-Not-Cancel-Tryjobs: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2152986
Commit-Queue: Mason Freed <masonfreedchromium.org>
Auto-Submit: Mason Freed <masonfreedchromium.org>
Reviewed-by: Kent Tamura <tkentchromium.org>
Cr-Commit-Position: refs/heads/master{#760705}

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wpt-commits: 8086723599f2bcdcbf54bcecff8cc50038cf939a
wpt-pr: 23072

UltraBlame original commit: b4489b28cd64543c78ab8aed7788fe827c346a1d