Add definitions for reactcss (#12122)

* Add definitions for react-css-transition-replace

* Add definitions for reactcss

* Change test header

* Remove accidentally added other definitions

* Remove yarn.lock from .gitignore

reactcss/reactcss.d.ts

@@ -0,0 +1,34 @@
+// Type definitions for ReactCSS v1.0.0
+// Project: http://reactcss.com/
+// Definitions by: Karol Janyst <https://github.com/LKay>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+/// <reference path="../react/react.d.ts" />
+
+declare namespace ReactCSS {
+    interface LoopableProps {
+        "first-child"?: boolean
+        "last-child"?: boolean
+        even?: boolean
+        odd?: boolean
+        [nthChild: string]: boolean
+    }
+
+    interface HoverProps {
+        hover?: boolean
+    }
+
+    interface Classes {
+        default: any
+        [scope: string]: any
+    }
+}
+
+declare module "reactcss" {
+    import React = __React
+
+    export type LoopableProps = ReactCSS.LoopableProps
+    export function hover<A>(component: React.ComponentClass<A> | React.StatelessComponent<A>): React.ComponentClass<A>
+    export function loop(i: number, length: number): ReactCSS.LoopableProps
+    export default function reactCSS (classes: ReactCSS.Classes, ...activations: Array<any>): any
+}