[css-grid] Swap columns and rows in grid-template shorthand

The spec was modified past December to change the order of
columns and rows in the grid-template shorthand:
https://github.com/w3c/csswg-drafts/commit/f6c7691679a519017a80ebae44fd86c3eae5c5f9

Updated the parsing and modified the tests to follow the new syntax.

BUG=583215

Review URL: https://codereview.chromium.org/1702013003

Cr-Commit-Position: refs/heads/master@{#376325}
33 files changed