test: add test to ensure comments are not stringified

Author: edison1105

packages/compiler-dom/__tests__/transforms/__snapshots__/stringifyStatic.spec.ts.snap

@@ -92,6 +92,22 @@ return function render(_ctx, _cache) {
 }"
 `;
 
+exports[`stringify static html > should not stringify comments 1`] = `
+"const { createCommentVNode: _createCommentVNode, createElementVNode: _createElementVNode, createStaticVNode: _createStaticVNode, Fragment: _Fragment, openBlock: _openBlock, createElementBlock: _createElementBlock } = Vue
+
+const _hoisted_1 = { class: "a" }
+
+return function render(_ctx, _cache) {
+  return (_openBlock(), _createElementBlock(_Fragment, null, [
+    _createCommentVNode(" Comment 1 "),
+    _createElementVNode("div", _hoisted_1, [
+      _createCommentVNode(" Comment 2 "),
+      _cache[0] || (_cache[0] = _createStaticVNode("<span class=\\"b\\"></span><span class=\\"b\\"></span><span class=\\"b\\"></span><span class=\\"b\\"></span><span class=\\"b\\"></span>", 5))
+    ])
+  ], 2112 /* STABLE_FRAGMENT, DEV_ROOT_FRAGMENT */))
+}"
+`;
+
 exports[`stringify static html > should work for <option> elements with string values 1`] = `
 "const { createElementVNode: _createElementVNode, createStaticVNode: _createStaticVNode, openBlock: _openBlock, createElementBlock: _createElementBlock } = Vue
 

packages/compiler-dom/__tests__/transforms/stringifyStatic.spec.ts

@@ -491,6 +491,16 @@ describe('stringify static html', () => {
     expect(code).toMatchSnapshot()
   })
 
+  test('should not stringify comments', () => {
+    const { code } = compileWithStringify(
+      `<!-- Comment 1 --><div class="a"><!-- Comment 2 -->${repeat(
+        `<span class="b"/>`,
+        StringifyThresholds.ELEMENT_WITH_BINDING_COUNT,
+      )}</div>`,
+    )
+    expect(code).toMatchSnapshot()
+  })
+
   test('should bail for <option> elements with null values', () => {
     const { ast, code } = compileWithStringify(
       `<div><select><option :value="null" />${repeat(