New InvalidationReasons: InvalidationBecameVisible and InvalidationBecameInvisible

The reasons will be displayed in tracing.
We can also pass more specific invalidation reasons via
WebInvalidationDebugAnnotations in the future.

BUG=410465

Review URL: https://codereview.chromium.org/577353005

git-svn-id: svn://svn.chromium.org/blink/trunk@182453 bbb929c8-8fbe-4397-9dbb-9b2b20218538