I agree with Phil:
And I don't see, why this only should be able to handle by big players like Google... PHP, Content Management Systems, etc. provide search-functions today. If there would be such a feature they would support that too, so that everybody who wants to use this, can use it.
I really don't see any problems.
Features like the new possibilities for forms in HTML5 were also ipossible with scripting, but there were much reasons, to also implement that declarative.
And the declarative way would have more benefits than only make it usable for people with scripting deactivated. Even if every browser would have Scripting without the possibility to deactivate that, this declarative way would have benefits for accessibility (screen-readers,...), usability and maybe even speed.
If this feature would be done declarative in HTML there is no duty to use it. But the webdesigners who want to have it that way, should be able to use that.