commit affcdceef73880b9b2d3b7a889e9da01bca26b8b
author hayato <hayato@chromium.org> Thu Apr 28 10:57:15 2016
committer Commit bot <commit-bot@chromium.org> Thu Apr 28 10:59:05 2016
tree 3e2ea7dd063dde22675c8c37064dfa1ab9585006
parent bd6e76400ea944185355bad53499494b1e778019

Clean up ShadowRootRareData, ShadowRoot and SlotAssignment

A lot of data are being scattered in these classes.

To make it clean and their responsibilities clear, remove ShadowRootRareData,
then move data owned by it into other classes:

- Make SlotAssignment have a responsibility of managing all data related to slot assignments
- Other data are now owned by ShadowRoot directly

BUG=531990

Review-Url: https://codereview.chromium.org/1925043002
Cr-Commit-Position: refs/heads/master@{#390345}