[gow] (2) Avoid inserting a <source> being the trigger for retrying t…

…he src='', since that makes no sense.

Fixing http://www.w3.org/Bugs/Public/show_bug.cgi?id=7631

git-svn-id: http://svn.whatwg.org/webapps@3924 340c8d12-0b0e-0410-8428-c7bf67bfef74

index

  <div class=impl>

  <p>If a <code><a href=#the-source-element>source</a></code> element is inserted as a child of a
  <a href=#media-element>media element</a> that is <a href=#in-a-document>in a
  <a href=#media-element>media element</a> that has no <code title=attr-media-src><a href=#attr-media-src>src</a></code> attribute and that is <a href=#in-a-document>in a
  <code>Document</code></a> and whose <code title=dom-media-networkState><a href=#dom-media-networkstate>networkState</a></code> has the value
  <code title=dom-media-NETWORK_EMPTY><a href=#dom-media-network_empty>NETWORK_EMPTY</a></code>, the user
  agent must invoke the <a href=#media-element>media element</a>'s <a href=#concept-media-load-algorithm title=concept-media-load-algorithm>resource selection

source

  <div class="impl">

  <p>If a <code>source</code> element is inserted as a child of a
  <span>media element</span> that is <span>in a
  <span>media element</span> that has no <code
  title="attr-media-src">src</code> attribute and that is <span>in a
  <code>Document</code></span> and whose <code
  title="dom-media-networkState">networkState</code> has the value
  <code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, the user