Capture and stop propagation on toolbar touch events. TinyMCE registers
the `touchstart` event on buttons, redirecting them as `click` events to
the button and preventing the default.

@see https://github.com/tinymce/tinymce/blob/abffb85/js/tinymce/classes/ui/Button.js#L57-L60
function disableToolbarTouchEvents() {
		editor.$( '.mce-toolbar:not(.mce-menubar)', document.body ).each( ( i, toolbar ) => {
			toolbar.addEventListener( 'touchstart', event => {
				event.stopImmediatePropagation();
			} );
		} );
	}