Migrate away from deprecated componentWillReceiveProps

This implementation is not ideal, but it works. The preferred alternative, getDerivedStateFromProps, does not have access to the previous properties and thus is insufficient for comparing new nodes to the old ones. This comparison is needed to determine whether the expensive node flattening method should be called or skipped.

Alternatively, the previous props could be stored in the state and thus be recalled in getDerivedStateFromProps.

src/js/CheckboxTree.js

@@ -95,12 +95,18 @@ class CheckboxTree extends React.Component {
         this.onCollapseAll = this.onCollapseAll.bind(this);
     }
 
-    componentWillReceiveProps({ nodes, checked, expanded }) {
+    shouldComponentUpdate({ nodes, checked, expanded }) {
+        // Since flattening nodes is an expensive task, only update the state when there is a change
         if (!isEqual(this.props.nodes, nodes)) {
             this.state.model.flattenNodes(nodes);
         }
 
         this.state.model.deserializeLists({ checked, expanded });
+
+        // Always update. We are hijacking this method to act as a hybrid between
+        // getDerivedStateFromProps and legacy componentWillReceiveProps, updating the internals
+        // of a state variable.
+        return true;
     }
 
     onCheck(nodeInfo) {