[Fix] functional SFC style injection support

Author: blake-newman

lib/component-normalizer.js

@@ -61,7 +61,16 @@ module.exports = function normalizeComponent (
     hook = injectStyles
   }
 
-  if (hook) {
+  if (hook && options.functional && injectStyles) {
+    // inject styles for functioal component in vue file
+    const existing = options.render
+    options.render = function renderWithStyleInjection (h, context) {
+      hook(context)
+      return existing(h, context)
+    }
+  }
+
+  if (hook && !options.functional) {
     // inject component registration as beforeCreate hook
     var existing = options.beforeCreate
     options.beforeCreate = existing