Rename backgrounded

Author: noamr

fetch.bs

@@ -2701,8 +2701,8 @@ functionality.
 <a for=/>fetch controller</a> or null).
 
 <p>A <dfn export>deferred fetch record</dfn> is a <a for=/>struct</a> used to maintain state needed
-to invoke a fetch at a later time, e.g., when a <code>Document</code> is unloaded or backgrounded. It
-has the following <a for=struct>items</a>:
+to invoke a fetch at a later time, e.g., when a <code>Document</code> is unloaded or becomes
+not <a for=Document>fully active</a>. It has the following <a for=struct>items</a>:
 
 <dl>
  <dt><dfn export for="deferred fetch record">request</dfn>