always use require for compoentNormalizer since it cannot be concatenated

Author: yyx990803

lib/loader.js

@@ -438,15 +438,9 @@ module.exports = function (content) {
   //   scopeId,
   //   moduleIdentifier (server only)
   // )
-  if (options.esModule) {
-    output += 'import normalizeComponent from ' +
-      loaderUtils.stringifyRequest(loaderContext, '!' + componentNormalizerPath) +
-    '\n'
-  } else {
-    output += 'var normalizeComponent = require(' +
-      loaderUtils.stringifyRequest(loaderContext, '!' + componentNormalizerPath) +
-    ')\n'
-  }
+  output += 'var normalizeComponent = require(' +
+    loaderUtils.stringifyRequest(loaderContext, '!' + componentNormalizerPath) +
+  ')\n'
 
   // <script>
   output += '/* script */\n'