Fix CodeSandbox warnings

Author: Oblosys

examples/parent-child-demo/jsconfig.json

@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "baseUrl": ".",
+    "experimentalDecorators": true
+  }
+}

examples/parent-child-demo/src/samples/Legacy.js

@@ -8,7 +8,7 @@ import LabeledCheckbox from '../components/LabeledCheckbox';
 import Tagged from '../components/Tagged';
 
 @traceLifecycle
-export default class Parent extends Component {
+class Parent extends Component {
   state = {
     showLastChild: true,
     x: 42
@@ -85,3 +85,5 @@ class Child extends Component {
     );
   }
 }
+
+export default Parent;

examples/parent-child-demo/src/samples/New.js

@@ -7,7 +7,7 @@ import LabeledCheckbox from '../components/LabeledCheckbox';
 import Tagged from '../components/Tagged';
 
 @traceLifecycle
-export default class Parent extends Component {
+class Parent extends Component {
   state = {
     showLastChild: true,
     x: 42
@@ -87,3 +87,5 @@ class Child extends Component {
     );
   }
 }
+
+export default Parent;