如何用JavaScript替换<head>中被两个HTML注释包裹的所有标签

我需要修改HTML文档的<head>标签：删除由两个特定注释（通过注释文本内容识别）包裹的所有内容（包含这两个注释本身），并替换为新的内容块。

替换前示例 #

<head>
  <title>My Website</title>
  <meta property="test" content="some content" />
  ...
  <!-- This is the first comment -->
  <meta property="hi" content="something" />
  <link rel="canonical" href="http://website.com/test/">
  <!-- This is the second comment -->
  ...
  <link rel="dns-prefetch" href="//use.typekit.net">
</head>

替换后示例 #

<head>
  <title>My Website</title>
  <meta property="test" content="some content" />
  ...
  <!-- This is the first NEW comment -->
  <meta property="hi" content="something new" />
  <link rel="canonical" href="http://website.com/hi-im-new/">
  <meta property="hiagain" content="something completely new" />
  <!-- This is the second NEW comment -->
  ...
  <link rel="dns-prefetch" href="//use.typekit.net">
</head>

内容的提问来源于stack exchange，提问作者user3371597