Generate getters/setters for text-stroke-width.

Currently, the text-stroke-width property is a 'storage_only' field, so
it has no generated public getters/setters. This patch changes it to an
'primitive' field so that its getters/setters can be generated as well.

BUG=628043

Review-Url: https://codereview.chromium.org/2907343002
Cr-Commit-Position: refs/heads/master@{#475461}
2 files changed