UIDS-211 Add arrow to Tooltip component (#212)

Author: rroppolo

spec/Storyshots.test.js

@@ -1,3 +1,4 @@
 import initStoryshots from '@storybook/addon-storyshots';
+import './__mocks__/reactDomMock';
 
 initStoryshots();

spec/__mocks__/reactDomMock.js

@@ -0,0 +1,11 @@
+// See: https://github.com/facebook/react/issues/11565
+// This appears to be a bug with React when testing modals
+// with react-test-renderer
+jest.mock('react-dom', () => {
+  const original = jest.requireActual('react-dom');
+
+  return {
+    ...original,
+    createPortal: (node) => node,
+  };
+});