split echarts into own file

build/webpack.prod.conf.js

@@ -86,6 +86,14 @@ var webpackConfig = merge(baseWebpackConfig, {
                 )
             }
         }),
+        // split echarts into its own file
+        new webpack.optimize.CommonsChunkPlugin({
+            async:'echarts',
+            minChunks(module) {
+                var context = module.context;
+                return context && (context.indexOf('echarts') >= 0 || context.indexOf('zrender') >= 0);
+            }
+        }),
         // extract webpack runtime and module manifest to its own file in order to
         // prevent vendor hash from being updated whenever app bundle is updated
         new webpack.optimize.CommonsChunkPlugin({