title: PHP detect browser support a tag
body: <p>For important tags, you may check it manually you check if browser is IE, FF, Opera, lynx! , ... 
  but you cannot check all ones. What I am looking for is such a php function(or even client side!):</p>
  
  <pre><code>is_supported_tag('&lt;bdi&gt;',$user_agent);
  </code></pre>
  
  <p><code>&lt;bdi&gt;</code> tag is a minor tag and runs on firefox and chrome only but later will be added to the other browsers and I look for rendering page automatically and not checking browser news each week!</p>
  
  <p>putting <code>&lt;bdi&gt;</code> tag will not make problem for other browsers but I'm worried about SEO to detect incompatibility.</p>
  
  <p>if browser does not support it, I want it to be removed.</p>
  
  <p>is there such a detection way?</p>