onTransitionEnd property Null safety

ElementStream<TransitionEvent> onTransitionEnd
@SupportedBrowser(SupportedBrowser.CHROME)@SupportedBrowser(SupportedBrowser.FIREFOX)@SupportedBrowser(SupportedBrowser.IE, '10')@SupportedBrowser(SupportedBrowser.SAFARI)

Stream of transitionend events handled by this Element.

Implementation

@SupportedBrowser(SupportedBrowser.CHROME)
@SupportedBrowser(SupportedBrowser.FIREFOX)
@SupportedBrowser(SupportedBrowser.IE, '10')
@SupportedBrowser(SupportedBrowser.SAFARI)
ElementStream<TransitionEvent> get onTransitionEnd =>
    transitionEndEvent.forElement(this);