use generated as gate in requestSetupBounds

Since ScrollStrategy is tagless, hasNode is always false. Using generated instead has the same effect to block against the subsequent calls until the client controls are rendered.
Merge pull request #1585 from enyojs/BHV-12786-ryanjduffy

Fixes BHV-12786

Looks good!

Reviewed-by: Aaron Tam (aaron.tam@lge.com)