retrofitted for IE8
constructor property defined only when __proto__ is not available
IE8 workaround for Object.defineProperty()
IE8 workaround for .isPrototypeOf()
feature detection methods moved to separate file and put directly on namespace
IE8 workaround for detection of .getOwnPropertyDescriptor()
package file
fix for IE8 obscuring overridden built-in methods
String.substr() shimmed
Array.indexOf() shimmed