Set displayName properly when patching React locally. (#1053)

* Using styled-jsx for with-jest example.

* Set the displayName of the wraped components.
Otherwise it won't get the correct displayName if the
original component doesn't provide it by using it's function name.

client/patch-react.js

@@ -107,6 +107,7 @@ function wrap (fn, around) {
 
   // copy all properties
   Object.assign(_fn, fn)
+  _fn.displayName = fn.displayName || fn.name
 
   _fn.prototype = fn.prototype