[LayoutNG] Fix broken layout while using CSS with writing modes.
1) This will set a writing mode to the fragment builder so it can be used at the time when we calculate a physical fragment.
2) Change computeMargin to accept 2 more parameters: Direction and writing mode.
TEST=NGBlockLayoutAlgorithmTest.LayoutBlockChildrenWithWritingMode
BUG=
635619
Committed:
https://crrev.com/085cf0072e0fee548055cb21e34ac66a12d73321
Cr-Commit-Position: refs/heads/master@{#419309}