feat(react): Support new flow 0.53 annotations (#209)

Author: danez

src/handlers/__tests__/flowTypeHandler-test.js

@@ -134,12 +134,24 @@ describe('flowTypeHandler', () => {
   }
 
   describe('TypeAlias', () => {
-    describe('class definition', () => {
+    describe('class definition for flow <0.53', () => {
       test(
         propTypesSrc => statement(template('class Foo extends Component<void, Props, void> {}', propTypesSrc))
       );
     });
 
+    describe('class definition for flow >=0.53 without State', () => {
+      test(
+        propTypesSrc => statement(template('class Foo extends Component<Props> {}', propTypesSrc))
+      );
+    });
+
+    describe('class definition for flow >=0.53 with State', () => {
+      test(
+        propTypesSrc => statement(template('class Foo extends Component<Props, State> {}', propTypesSrc))
+      );
+    });
+
     describe('class definition with inline props', () => {
       test(
           propTypesSrc => statement(template('class Foo extends Component { props: Props; }', propTypesSrc))

src/utils/getFlowTypeFromReactComponent.js

@@ -32,7 +32,12 @@ export default (path: NodePath): ?NodePath  => {
     const superTypes = path.get('superTypeParameters');
 
     if (superTypes.value) {
-      typePath = superTypes.get('params').get(1);
+      const params = superTypes.get('params');
+      if (params.value.length === 3) {
+        typePath = params.get(1);
+      } else {
+       typePath = params.get(0);
+      }
     } else {
       const propsMemberPath = getMemberValuePath(path, 'props');
       if (!propsMemberPath) {