Support fixed-layout table and a part of anonymous table object

This is a rebase of #1548 on recent master.

There have been many changes since #1548 is first uploaded, so I'm creating new PR.
This PR includes:
 - construction of table-* flows (table-wrapper, table-caption, table, table-rowgroup, table-row, table-cell)
 - fixed-layout table calculation
 - a part of anonymous table object implementation 
[CSS 2.1, 17.2.1](http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes) (Step 1-1, 1-2, Step 2)