Generic type arguments in JSX elements

JSX elements now allow passing type arguments to generic components.

Example

class GenericComponent<P> extends React.Component<P> {
    internalProp: P;
}
type Props = { a: number; b: string; };
const x = <GenericComponent<Props> a={10} b="hi"/>; // OK
const y = <GenericComponent<Props> a={10} b={20} />; // Error