Re-enable css transitions for dropdowns in header, needs menu-droppo library update

ui/app/app.js

@@ -218,6 +218,7 @@ App.prototype.renderNetworkDropdown = function () {
   const isOpen = state.isNetworkMenuOpen
 
   return h(Dropdown, {
+    useCssTransition: true,
     isOpen,
     onClickOutside: (event) => {
       const { classList } = event.target
@@ -355,6 +356,7 @@ App.prototype.renderDropdown = function () {
   const isOpen = state.isMainMenuOpen
 
   return h(Dropdown, {
+    useCssTransition: true,
     isOpen: isOpen,
     zIndex: 11,
     onClickOutside: (event) => {

ui/app/components/account-dropdowns.js

@@ -65,6 +65,7 @@ class AccountDropdowns extends Component {
     return h(
       Dropdown,
       {
+        useCssTransition: true, // Hardcoded because account selector is temporarily in app-header
         style: {
           marginLeft: '-238px',
           marginTop: '38px',

ui/app/components/dropdown.js

@@ -8,7 +8,7 @@ const noop = () => {}
 
 class Dropdown extends Component {
   render () {
-    const { isOpen, onClickOutside, style, innerStyle, children } = this.props
+    const { isOpen, onClickOutside, style, innerStyle, children, useCssTransition } = this.props
 
     const innerStyleDefaults = extend({
       borderRadius: '4px',
@@ -20,6 +20,7 @@ class Dropdown extends Component {
     return h(
       MenuDroppo,
       {
+        useCssTransition,
         isOpen,
         zIndex: 11,
         onClickOutside,
@@ -43,6 +44,7 @@ class Dropdown extends Component {
 Dropdown.defaultProps = {
   isOpen: false,
   onClick: noop,
+  useCssTransition: false,
 }
 
 Dropdown.propTypes = {