refactor: use more efficient walk for importUsageCheck

packages/compiler-sfc/src/script/importUsageCheck.ts

@@ -5,8 +5,8 @@ import {
   SimpleExpressionNode,
   forAliasRE,
   parserOptions,
-  transform,
-  walkIdentifiers
+  walkIdentifiers,
+  TemplateChildNode
 } from '@vue/compiler-dom'
 import { createCache } from '../cache'
 import { camelize, capitalize, isBuiltInDirective } from '@vue/shared'
@@ -34,10 +34,12 @@ function resolveTemplateUsageCheckString(sfc: SFCDescriptor) {
   }
 
   let code = ''
-  transform(ast, {
-    nodeTransforms: [
-      node => {
-        if (node.type === NodeTypes.ELEMENT) {
+
+  ast!.children.forEach(walk)
+
+  function walk(node: TemplateChildNode) {
+    switch (node.type) {
+      case NodeTypes.ELEMENT:
         if (
           !parserOptions.isNativeTag!(node.tag) &&
           !parserOptions.isBuiltInComponent!(node.tag)
@@ -73,14 +75,13 @@ function resolveTemplateUsageCheckString(sfc: SFCDescriptor) {
             code += `,${prop.value.content}`
           }
         }
-        } else if (node.type === NodeTypes.INTERPOLATION) {
-          code += `,${processExp(
-            (node.content as SimpleExpressionNode).content
-          )}`
+        node.children.forEach(walk)
+        break
+      case NodeTypes.INTERPOLATION:
+        code += `,${processExp((node.content as SimpleExpressionNode).content)}`
+        break
     }
   }
-    ]
-  })
 
   code += ';'
   templateUsageCheckCache.set(content, code)