Fix style-prop-object crash (fixes #834)

Author: yannickcr

lib/rules/style-prop-object.js

@@ -62,7 +62,7 @@ module.exports = {
       },
 
       JSXAttribute: function(node) {
-        if (node.name.name !== 'style') {
+        if (!node.value || node.name.name !== 'style') {
           return;
         }
 

tests/lib/rules/style-prop-object.js

@@ -102,6 +102,10 @@ ruleTester.run('style-prop-object', rule, {
         'React.createElement("div", { style: styles });'
       ].join('\n'),
       parserOptions: Object.assign({sourceType: 'module'}, parserOptions)
+    },
+    {
+      code: '<div style></div>',
+      parserOptions: parserOptions
     }
   ],
   invalid: [