Moved text-align to be generated in ComputedStyleBase.

Move the inherited property text-align and its enum, ETextAlign,
to be generated in ComputedStyleBase. Also moved getter / setter /
initial value methods to be generated in ComputedStyleBase.

BUG=628043

Review-Url: https://codereview.chromium.org/2577973002
Cr-Commit-Position: refs/heads/master@{#438781}
4 files changed