Fix IE11 test_scroll failures.
Trident is more like IE9+ than we would have guessed.

Also disabling quirks and loose tests for IE9+.
On IE9+, an <iframe> will always run with the doctype of the main
document, regardless of what URL is loaded into the iframe.

Fixes #18124, refs #17311.

(cherry picked from commit a832214a342b6e03ad4a9b1669fae71c7938c44b)

Conflicts:
	window.js