[web-animations-1] Fix some erroneous references to property keyframes

In the "process a keyframes argument" procedure there are a number of
references to 'property keyframes' and one reference to
'property-indexed keyframe' that should refer to 'processed keyframes'.

This fixes #2119.

Author: birtles

web-animations-1/Overview.bs

@@ -5228,7 +5228,7 @@ keyframes using the following procedure:
 
         1.  Assign each value in <var>offsets</var> to the <a>keyframe
             offset</a> of the <a>keyframe</a> with corresponding position in
-            <var>property keyframes</var> until the end of either sequence is
+            <var>processed keyframes</var> until the end of either sequence is
             reached.
 
         1.  Let <var>easings</var> be a sequence of <code>DOMString</code>
@@ -5251,29 +5251,29 @@ keyframes using the following procedure:
             of length one containing the single value &ldquo;linear&rdquo;, i.e.
             &laquo;&nbsp;"linear"&nbsp;&raquo;.
 
-        1.  If <var>easings</var> has fewer items than <var>property
+        1.  If <var>easings</var> has fewer items than <var>processed
             keyframes</var>, repeat the elements in <var>easings</var>
             successively starting from the beginning of the list until
-            <var>easings</var> has as many items as <var>property
+            <var>easings</var> has as many items as <var>processed
             keyframes</var>.
 
             <div class=example>
-            For example, if <var>property-indexed keyframe</var> has
+            For example, if <var>processed keyframes</var> has
             five items, and <var>easings</var> is the sequence
             &laquo;&nbsp;"ease-in", "ease-out"&nbsp;&raquo;,
             <var>easings</var> would be repeated to become
             &laquo;&nbsp;"ease-in", "ease-out", "ease-in", "ease-out",
             "ease-in"&nbsp;&raquo;.
             </div>
 
-        1.  If <var>easings</var> has more items than <var>property
+        1.  If <var>easings</var> has more items than <var>processed
             keyframes</var>, store the excess items as <var>unused
             easings</var>.
 
         1.  Assign each value in <var>easings</var> to a property named
             &ldquo;easing&rdquo; on the <a>keyframe</a> with the corresponding
-            position in <var>property keyframes</var> until the end of
-            <var>property keyframes</var> is reached.
+            position in <var>processed keyframes</var> until the end of
+            <var>processed keyframes</var> is reached.
 
         1.  If the &ldquo;composite&rdquo; member of the <var>property-indexed
             keyframe</var> is <em>not</em> an empty sequence:
@@ -5286,16 +5286,16 @@ keyframes using the following procedure:
                 the value of the &ldquo;composite&rdquo; as its single item.
 
             1.  As with <var>easings</var>, if <var>composite modes</var>
-                has fewer items than <var>property keyframes</var>, repeat the
+                has fewer items than <var>processed keyframes</var>, repeat the
                 elements in <var>composite modes</var> successively starting
                 from the beginning of the list until <var>composite modes</var>
-                has as many items as <var>property keyframes</var>.
+                has as many items as <var>processed keyframes</var>.
 
             1.  Assign each value in <var>composite modes</var> to the
                 <a>keyframe-specific composite operation</a> on the
-                <a>keyframe</a> with the corresponding position in <var>property
-                keyframes</var> until the end of <var>property keyframes</var>
-                is reached.
+                <a>keyframe</a> with the corresponding position in
+                <var>processed keyframes</var> until the end of <var>processed
+                keyframes</var> is reached.
 
     </div>