Fix ES6 support using Babel::Transpiler

Tested on sprockets 3.7.1 with sprockets-es6 0.9.2, but should also work
on sprockets 4.x with babel-transpiler gem.

This also allows to use ES6 `export default` for defining components.

Author: felixbuenemann

lib/sprockets/vue/script.rb

@@ -12,7 +12,16 @@ class << self
           CoffeeScript.compile(s, sourceMap: true, sourceFiles: [input[:source_path]], no_wrap: true)
         },
         'es6' => ->(s, input){
-          Babel::Transpiler.transform(data, {}) #TODO
+          opts = {
+            'sourceRoot' => input[:load_path],
+            'moduleRoot' => nil,
+            'filename' => input[:filename],
+            'filenameRelative' => input[:environment].split_subpath(input[:load_path], input[:filename])
+          }
+
+          result = Babel::Transpiler.transform(s, opts)
+
+          { 'js' => result['code'] }
         },
         nil => ->(s,input){ { 'js' => s } }
       }
@@ -30,7 +39,7 @@ def call(input)
             map = result['sourceMap']
 
             output << "'object' != typeof VComponents && (this.VComponents = {});
-              var module = { exports: null };
+              var module = { exports: null }, exports = {};
               #{result['js']}; VComponents['#{name}'] = module.exports;"
           end