catch edge case where React.createClass() is called with nothing

Author: Keyan Zhang

transforms/__testfixtures__/class.input.js

@@ -171,3 +171,5 @@ var SingleArgArrowFunction = React.createClass({
 
 var mySpec = {};
 var NotAnObjectLiteral = React.createClass(mySpec);
+
+var WaitWhat = React.createClass();

transforms/__testfixtures__/class.output.js

@@ -167,3 +167,5 @@ class SingleArgArrowFunction extends React.Component {
 
 var mySpec = {};
 var NotAnObjectLiteral = React.createClass(mySpec);
+
+var WaitWhat = React.createClass();

transforms/utils/ReactUtils.js

@@ -102,7 +102,7 @@ module.exports = function(j) {
     const args = callCollection.get('arguments').value;
     if (args) {
       const spec = args[0];
-      if (spec.type === 'ObjectExpression' && Array.isArray(spec.properties)) {
+      if (spec && spec.type === 'ObjectExpression' && Array.isArray(spec.properties)) {
         return spec;
       }
     }