Fix multiple var declarations in transform-react-constant-elements (#5732) (#5756)

This was broken by a legacy attachment path conditional that
is no longer needed.

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/append-to-end-when-declared-in-scope/expected.js

@@ -4,8 +4,9 @@ export default class App extends React.Component {
   }
 }
 
-const _ref2 = <div>child</div>,
-      AppItem = () => {
+var _ref2 = <div>child</div>;
+
+const AppItem = () => {
   return _ref2;
 },
       _ref = <div>

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/compound-assignment/actual.js

@@ -0,0 +1,5 @@
+import React from 'react';
+import Loader from 'loader';
+
+const errorComesHere = () => <Loader className="full-height"/>,
+  thisWorksFine = () => <Loader className="p-y-5"/>;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/compound-assignment/expected.js

@@ -0,0 +1,9 @@
+import React from 'react';
+import Loader from 'loader';
+
+var _ref = <Loader className="full-height" />;
+
+var _ref2 = <Loader className="p-y-5" />;
+
+const errorComesHere = () => _ref,
+      thisWorksFine = () => _ref2;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/dont-hoist-before-class/expected.js

@@ -4,10 +4,11 @@ const Parent = ({}) => _ref;
 
 export default Parent;
 
-let _ref2 = <div className="child">
+var _ref2 = <div className="child">
     ChildTextContent
-  </div>,
-    Child = () => _ref2,
+  </div>;
+
+let Child = () => _ref2,
     _ref = <div className="parent">
     <Child />
-  </div>;
+  </div>;