Describe repeating/truncation behavior for uneven length lists, using rules where transition-property is the important length.

This resolves https://www.w3.org/Bugs/Public/show_bug.cgi?id=14604
as proposed in
http://lists.w3.org/Archives/Public/www-style/2012Mar/0013.html and
resolved in the 2012 February 29 teleconference (minutes at
http://lists.w3.org/Archives/Public/www-style/2012Mar/0013.html ).

Author: dbaron

css3-transitions/Overview.html

@@ -282,14 +282,23 @@ <h2 id=transitions><span class=secno>2. </span>Transitions</h2>
    transition over a period of two seconds and the left property to
    transition over a period of four seconds.</div>
 
-  <p> In the case where the list of values in transition properties do not
-   have the same length, the list is repeated as a whole in order to provide
-   necessary values.
-
-  <p class=issue> Issue: Are the lists repeated to all be the length of the
-   longest list, or are they repeated or truncated to match the length of the
+  <p> In the case where the lists of values in transition properties do not
+   have the same length, the length of the &lsquo;<a
+   href="#transition-property"><code
+   class=property>transition-property</code></a>&rsquo; list determines the
+   number of items in each list examined when starting transitions. The lists
+   are matched up from the first value: excess values at the end are not
+   used. If one of the other properties doesn't have enough comma-separated
+   values to match the number of values of &lsquo;<a
+   href="#transition-property"><code
+   class=property>transition-property</code></a>&rsquo;, the UA must
+   calculate its used value by repeating the list of values until there are
+   enough. This truncation or repetition does not affect the computed value.
+   <span class=note> Note: This is analogous to the behavior of the
+   &lsquo;<code class=css>background-*</code>&rsquo; properties, with
+   &lsquo;<code class=property>background-image</code>&rsquo; analogous to
    &lsquo;<a href="#transition-property"><code
-   class=property>transition-property</code></a>&rsquo; list?
+   class=property>transition-property</code></a>&rsquo;. </span>
 
   <div class=example>
    <p style="display:none"> Example(s):</p>

css3-transitions/Overview.src.html

@@ -138,17 +138,25 @@ <h2 id="transitions">Transitions</h2>
 
   </pre>This will cause the <code class="property">'opacity'</code> property to transition over a period of two seconds and the left property to transition over a period of four seconds.
       </div>
-      
+
       <p>
-        In the case where the list of values in transition properties do not have
-        the same length, the list is repeated as a whole in order to provide necessary values.
-      </p>
-      <p class="issue">
-        Issue: Are the lists repeated to all be the length of the
-        longest list, or are they repeated or truncated to match the
-        length of the 'transition-property' list?
+        In the case where the lists of values in transition properties
+        do not have the same length, the length of the
+        'transition-property' list determines the number of items in
+        each list examined when starting transitions.  The lists are
+        matched up from the first value: excess values at the end are
+        not used.  If one of the other properties doesn't have enough
+        comma-separated values to match the number of values of
+        'transition-property', the UA must calculate its used value by
+        repeating the list of values until there are enough.  This
+        truncation or repetition does not affect the computed value.
+        <span class="note">
+          Note: This is analogous to the behavior of the 'background-*'
+          properties, with 'background-image' analogous to
+          'transition-property'.
+        </span>
       </p>
-      
+
       <div class="example">
         <p style="display:none">
           Example(s):