".linenums .tag" should be ".prettyprint .tag".

[tekezo]

prettyprint does not apply a color to XML tag when we use the default prettyprint.css.
.linunums .tag should be .prettyprint .tag.
This patch resolves this prettyprint color issue.

<pre class="prettyprint lang-xml">
&lt;root&gt;
&lt;item&gt;item1&lt;/item&gt;
&lt;item&gt;item2&lt;/item&gt;
&lt;item&gt;item3&lt;/item&gt;
&lt;/root&gt;
</pre>

[mdo]

Merged into 2.1.0-wip. Thanks!