Revert "moved the modernizr placeholder fix from go-local-subscriptions to to-ui"

it turns out we don't need the placeholder workaround for our supported list of browsers. This addresses a comment from https://github.com/GigaOM/go-local-subscriptions/pull/1

This reverts commit a7fec7611e4faadbe9b08eb260025367a3657d13.

as part of the work on https://github.com/GigaOM/legacy-pro/issues/4055