Editorial: replace data-export="" with just export

[foolip]

Using export="" in the source will result in data-export="" in the
output, so this doesn't change anything.

---

/media.html ( diff )

[foolip]

Diff of the changes this results in. Just the timestamp and the order of attributes in one case:

@@ -30,7 +30,7 @@
     <div>
      <a href=https://github.com/whatwg/html class=changes><span><strong>Contribute on GitHub</strong> <code>whatwg/html repository</code></span></a>
      <a href=https://github.com/whatwg/html/commits class=changes><span><strong>Commits</strong> <code>on GitHub</code></span></a>
-     <a id=commit-snapshot-link href=/commit-snapshots/19be46f7d417ef436ca95edbf00ac48bc658cb86/ class=changes><span><strong>Snapshot</strong> <code>as of this commit</code></span></a>
+     <a id=commit-snapshot-link href=/commit-snapshots/ff5d02e661e28afd566654008dc3e6c1bbef157a/ class=changes><span><strong>Snapshot</strong> <code>as of this commit</code></span></a>
      <a href=https://twitter.com/htmlstandard class=changes><span><strong>Twitter Updates</strong> <code>@htmlstandard</code></span></a>
     </div>
     <div>
@@ -27674,7 +27674,7 @@
   if called with an <var>index</var> argument greater than or equal to the number of ranges
   represented by the object.</p>
 
-  <p>When a <code id=time-ranges:timeranges-2><a href=#timeranges>TimeRanges</a></code> object is said to be a <dfn data-export="" id=normalised-timeranges-object>normalized <code>TimeRanges</code> object</dfn>,
+  <p>When a <code id=time-ranges:timeranges-2><a href=#timeranges>TimeRanges</a></code> object is said to be a <dfn id=normalised-timeranges-object data-export="">normalized <code>TimeRanges</code> object</dfn>,
   the ranges it represents must obey the following criteria:</p>
 
   <ul><li>The start of a range must be greater than the end of all earlier ranges.<li>The start of a range must be less than or equal to the end of that same range.</ul>

[foolip]

The background here is that #5916 rewrote lots of data-export="" to export after @sideshowbarker added support in Wattsi. The cases I've found here were probably in PRs at the time, and perhaps some copy-pasting after that.

[foolip]

I found this while working on whatwg/html-build#296.