Generate getters/setters for line-height-step.

Currently, the line-height-step property is a 'storage_only' field, so
it has no generated public getters/setters. This patch changes it to an
'primitive' field so that their getters/setters can be generated as well.

Diff of generated files:
https://gist.github.com/darrnshn/c7aa4490604c306177cacf258e2038f4/revisions

BUG=628043

Review-Url: https://codereview.chromium.org/2895143002
Cr-Commit-Position: refs/heads/master@{#474585}
2 files changed