fix(utils): Shim Element in non-DOM environments (#1387)

The function `DOMElement` in `utils.js` throws a `ReferenceError` in non-DOM environments such as Node, due to the fact that it references `Element` on the right-hand side  of an `instanceof` check, which is (most probably) undefined in non-DOM environments.

This pull request adds a small shim for the `Element` object in order to prevent `DOMElement` from throwing an error if `Element` is not defined.

src/utils.js

@@ -113,6 +113,9 @@ export function deprecated(propType, explanation) {
   };
 }
 
+// Shim Element if needed (e.g. in Node environment)
+const Element = typeof window === 'object' && window.Element || function() {};
+
 export function DOMElement(props, propName, componentName) {
   if (!(props[propName] instanceof Element)) {
     return new Error(