fix(cli): compatible with @vue/cli-plugin-babel@4.2.3 #1394

packages/webpack-uni-mp-loader/lib/babel/plugin-dynamic-import.js

 const t = require('@babel/types')
 const babelTemplate = require('@babel/template').default
 
-const buildDynamicImport = babelTemplate(`var IMPORT_NAME = ()=>import(IMPORT_SOURCE)`, {
-  preserveComments: true,
-  plugins: [
-    'dynamicImport'
-  ]
-})
+// const buildDynamicImport = babelTemplate(`var IMPORT_NAME = ()=>import(IMPORT_SOURCE)`, {
+//   preserveComments: true,
+//   plugins: [
+//     'dynamicImport'
+//   ]
+// })
+// 已废弃，@vue/cli-plugin-babel@4 增加了 dynamic import 转换
 // var test = ()=>import(/* webpackChunkName: "components/test" */'../../components/test')
-function getDynamicImport (name, source, chunkName) {
-  const stringLiteral = t.stringLiteral(source)
-  const dynamicImportComment = {
-    type: 'CommentBlock',
-    value: `webpackChunkName: "${chunkName}"`
-  }
-  stringLiteral.leadingComments = [dynamicImportComment]
-  return buildDynamicImport({
+// function getDynamicImport (name, source, chunkName) {
+//   const stringLiteral = t.stringLiteral(source)
+//   const dynamicImportComment = {
+//     type: 'CommentBlock',
+//     value: `webpackChunkName: "${chunkName}"`
+//   }
+//   stringLiteral.leadingComments = [dynamicImportComment]
+//   return buildDynamicImport({
+//     IMPORT_NAME: t.identifier(name),
+//     IMPORT_SOURCE: stringLiteral
+//   })
+// }
+// var test = function(resolve) {require.ensure([], () => resolve(require('../../components/test')),'components/test')}
+const buildRequireEnsure = babelTemplate(
+  `var IMPORT_NAME = function(){require.ensure([],()=>resolve(require(IMPORT_SOURCE)),CHUNK_NAME)}`
+)
+
+function getRequireEnsure (name, source, chunkName) {
+  return buildRequireEnsure({
     IMPORT_NAME: t.identifier(name),
-    IMPORT_SOURCE: stringLiteral
+    IMPORT_SOURCE: t.stringLiteral(source),
+    CHUNK_NAME: t.stringLiteral(chunkName)
   })
 }
 
@@ -30,7 +43,7 @@ module.exports = function ({
         const dynamicImport = state.opts.dynamicImports[path.node.source.value]
         if (dynamicImport) {
           path.insertBefore(
-            getDynamicImport(
+            getRequireEnsure(
               path.node.specifiers[0].local.name,
               dynamicImport.source,
               dynamicImport.chunkName