Core: trigger events for elements outside their form

improves jquery-validation#2156

src/core.js

@@ -424,6 +424,15 @@ $.extend( $.validator, {
 				// Support: Chrome, oldIE
 				// "select" is provided as event.target when clicking a option
 				.on( "click.validate", "select, option, [type='radio'], [type='checkbox']", delegate );
+			$( this.currentForm.elements ).filter( function( i, el ) {
+				return $( el ).closest( el.form ).length === 0;
+			} )
+				.filter( ":text, [type='password'], [type='file'], select, textarea, [type='number'], [type='search'], " +
+					"[type='tel'], [type='url'], [type='email'], [type='datetime'], [type='date'], [type='month'], " +
+					"[type='week'], [type='time'], [type='datetime-local'], [type='range'], [type='color'], " +
+					"[type='radio'], [type='checkbox'], [type='button']" )
+					.on( "focusin.validate focusout.validate keyup.validate", delegate ).end()
+				.filter( "select, option, [type='radio'], [type='checkbox']" ).on( "click.validate", delegate );
 
 			if ( this.settings.invalidHandler ) {
 				$( this.currentForm ).on( "invalid-form.validate", this.settings.invalidHandler );