Improved handling of tree-builder fixup.

* Improved detection of when tree-builder fixes up the DOM
  because of misnested tags in source.

  - HTML5TreeBuilder now adds unique numeric tag ids to
    start tags. These are now used to associate start tags
    with shadow meta-tags added.

  - Since tsr is no longer in the picture, detection of
    auto-inserted start and end tags is not affected by
    where they show up.  With this change, removed some older
    hacky code/checks that tried to make decisions about when
    to look for auto-inserted start and end tags.

* Regenerated selser changes and updated blacklist.

* Removed two whitelisted tests since output from them is clearly
  broken and needs fixing:

  ------------
  External link containing double-single-quotes in text embedded
  in * italics (bug 4598 sanity check)
  ------------
  Link containing double-single-quotes '' in text embedded in italics
  (bug 4598 sanity check)
  ------------

Change-Id: If290aa7f7df1a5baf3ddf2a9ad36cfa39d66c8d4
Merge "Improved handling of tree-builder fixup."