Function extend

tests/qunit.js:999–1011

(a, b)

}

function extend(a, b) {
	for ( var prop in b ) {
		if ( b[prop] === undefined ) {
			delete a[prop];

		// Avoid "Member not found" error in IE8 caused by setting window.constructor
		} else if ( prop !== "constructor" || a !== window ) {
			a[prop] = b[prop];
		}
	}

	return a;
}

function addEvent(elem, type, fn) {
	if ( elem.addEventListener ) {