• Fixed xhr.abort() to no longer give an exception when the constructed XMLHttpRequest was invalid. (@whamtet)
• Fixed event.getModifierState() on MouseEvent and KeyboardEvent instances to properly consult the ctrlKey, altKey, metaKey, and shiftKey properties of the event. (@juzerzarif)
• Fixed custom element creation to not be affected by any modifications to the window.customElements property. (@bicknellr)