[webcomponents] Address @othermaciej's feedback to "Constructor-Dmitry" (#297)

See https://lists.w3.org/Archives/Public/public-webapps/2015JulSep/0311.html. Mainly, ensures that parser-created elements are created via a new set of steps that runs things synchronously while suspending the parser, instead of upgrading them. Also points out the problems that could cause upgrades to happen with an incomplete set of children present.
You can view, comment on, or merge this pull request online at:

  https://github.com/w3c/webcomponents/pull/297

-- Commit Summary --

  * Address @othermaciej's feedback to "Constructor-Dmitry"

-- File Changes --

    M proposals/Constructor-Dmitry.md (58)

-- Patch Links --

https://github.com/w3c/webcomponents/pull/297.patch
https://github.com/w3c/webcomponents/pull/297.diff

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/pull/297