Extension Docs: Remove out dated version notes.

chrome/common/extensions/docs/static/xhr.html

 <div id="pageData-name" class="pageData">Cross-Origin XMLHttpRequest</div>
 
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 <p id="classSummary">
 Regular web pages can use the
 <a href="http://www.w3.org/TR/XMLHttpRequest/">XMLHttpRequest</a>
 object to send and receive data from remote servers,
 but they're limited by the
 <a href="http://en.wikipedia.org/wiki/Same_origin_policy">same origin policy</a>.
 Extensions aren't so limited.
 An extension can talk to remote servers outside of its origin,
 as long as it first requests cross-origin permissions.</p>
 
-<p class="note">
-<b>Version note:</b>
-As of Chrome 13,
-content scripts can make cross-origin requests
-to the same servers as the rest of the extension.
-Before Chrome 13, a content script couldn't directly make requests;
-instead, it had to
-send a message to its parent extension
-asking the extension to make a cross-origin request.
-</p>
-
 <h2 id="extension-origin">Extension origin</h2>
 <p>Each running extension exists within its own separate security origin. Without
 requesting additional privileges, the extension can use
 XMLHttpRequest to get resources within its installation. For example, if
 an extension contains a JSON configuration file called <code>config.json</code>,
 in a <code>config_resources</code> folder, the extension can retrieve the file's contents like
 this:</p>
 
 <pre>
 var xhr = new XMLHttpRequest();
@@ skipping 119 matching lines @@
 </pre>
 <p>
 Additionally, be especially careful of resources retrieved via HTTP.  If your
 extension is used on a hostile network, an network attacker (aka a <a
 href="http://en.wikipedia.org/wiki/Man-in-the-middle_attack">"man-in-the-middle"</a>)
 could modify the response and, potentially, attack your extension.  Instead,
 prefer HTTPS whenever possible.
 </p>
 
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