Implement a parent check in sectionRowIndex

Implement a parent check in sectionRowIndex [1], the parent
of the table row has to be a table or a section element, if not
we need to return -1.

Behavior matches Firefox, Safari and Edge.

BUG=651762

[1] https://html.spec.whatwg.org/multipage/tables.html#dom-tr-sectionrowindex

Review-Url: https://codereview.chromium.org/2409773002
Cr-Commit-Position: refs/heads/master@{#424562}
2 files changed