fix(compiler-sfc): support complex expression in CSS v-bind() (#5114)

fix #5109

packages/compiler-sfc/__tests__/__snapshots__/cssVars.spec.ts.snap

@@ -66,6 +66,27 @@ return { color, width }
 }"
 `;
 
+exports[`CSS vars injection codegen should work with w/ complex expression 1`] = `
+"import { useCssVars as _useCssVars, unref as _unref } from 'vue'
+
+export default {
+  setup(__props, { expose }) {
+  expose();
+
+_useCssVars(_ctx => ({
+  \\"xxxxxxxx-_a___b____2____px__\\": ((_unref(a) + _unref(b)) / 2 + 'px' ),
+  \\"xxxxxxxx-__a___b______2___a_\\": (((_unref(a) + _unref(b))) / (2 * _unref(a)))
+}))
+
+        let a = 100
+        let b = 200
+        
+return { a, b }
+}
+
+}"
+`;
+
 exports[`CSS vars injection codegen w/ <script setup> 1`] = `
 "import { useCssVars as _useCssVars, unref as _unref } from 'vue'