Fixed more lint errors.

src/components/modals/AddModal.jsx

@@ -55,7 +55,7 @@ class AddModal extends React.Component {
     }
   }
 
-  componentWillUpdate(nextProps, nextState) {
+  UNSAFE_componentWillUpdate(nextProps, nextState) {
     // Check if source is valid for new type
     const oldType = this.state.type;
     const newType = nextState.type;

src/components/sources/SourceTypeEditor.jsx

@@ -11,6 +11,7 @@ class TileJSONSourceEditor extends React.Component {
   static propTypes = {
     source: PropTypes.object.isRequired,
     onChange: PropTypes.func.isRequired,
+    children: PropTypes.node,
   }
 
   render() {
@@ -33,6 +34,7 @@ class TileURLSourceEditor extends React.Component {
   static propTypes = {
     source: PropTypes.object.isRequired,
     onChange: PropTypes.func.isRequired,
+    children: PropTypes.node,
   }
 
   changeTileUrl(idx, value) {