ignore _generated FunctionDeclarations too in es6.spec.symbols transformer

src/babel/transformation/file/index.js

@@ -387,6 +387,7 @@ export default class File {
         unique: true
       });
     }
+
     return uid;
   }
 

src/babel/transformation/transformers/es6/spec.symbols.js

@@ -33,3 +33,5 @@ export function BinaryExpression(node, parent, scope, file) {
 export function VariableDeclaration(node) {
   if (node._generated) this.skip();
 }
+
+export { VariableDeclaration as FunctionDeclaration };