Revert "fixes #17751 use native placeholder support for form inputs"

This reverts commit 63486c0569d7ba60e351cf01f36dd8f007ed3b48.

This commit caused backwards-incompatible changes to the toolkit
that will break existing users, and introduces a feature that
is not cross-browser compatible (HTML5 placeholder styling is
not consistent) in order to fix an unrelated defect.