dont rerender placeholder during menu closing (#68)

* dont rerender placeholder during menu closing

* documentation comment

Author: madox2

src/MenuPlaceholder.js

@@ -9,6 +9,11 @@ export default class MenuPlaceholder extends Component {
     this.state = {};
   }
 
+  shouldComponentUpdate() {
+    // don't terminate closing animation
+    return !this.props.ctx._isMenuClosing;
+  }
+
   render() {
     const { ctx, backdropStyles } = this.props;
     const shouldRenderMenu = ctx.isMenuOpen() && ctx._isInitialized();

src/MenuProvider.js

@@ -19,6 +19,7 @@ export default class MenuProvider extends Component {
   constructor(props) {
     super(props);
     this._menuRegistry = makeMenuRegistry();
+    this._isMenuClosing = false;
   }
 
   getChildContext() {
@@ -115,7 +116,15 @@ export default class MenuProvider extends Component {
       && this.optionsRef.close()) || Promise.resolve();
     const hideBackdrop = this.backdropRef && this.backdropRef.close();
     this._invalidateTriggerLayouts();
-    return Promise.all([hideMenu, hideBackdrop]);
+    this._isMenuClosing = true;
+    return Promise.all([hideMenu, hideBackdrop])
+      .then(() => {
+        this._isMenuClosing = false;
+      })
+      .catch(err => {
+        this._isMenuClosing = false;
+        throw err;
+      })
   }
 
   toggleMenu(name) {