Deal with Cf category better.

Author: fantasai

css3-text/Overview.html

@@ -686,8 +686,8 @@ <h2 id=white-space-processing><span class=secno>3. </span> White Space
    href="http://www.w3.org/TR/CSS21/visuren.html#anonymous">9.2.2.1</a>
 
   <p>Control characters (Unicode class Cc) other than tab (U+0009), line feed
-   (U+000A), space (U+0020), and the bidi formatting characters
-   (U+202<var>x</var>) are ignored for the purpose of rendering.
+   (U+000A), and carriage return (U+000D) are ignored for the purpose of
+   rendering.
 
   <h3 id=white-space-collapsing><span class=secno>3.1. </span> White Space
    Collapsing: the &lsquo;<a href="#text-space-collapse"><code
@@ -2817,6 +2817,12 @@ <h3 id=letter-spacing><span class=secno>8.2. </span> Tracking: the
     connections, it should not apply letter-spacing between characters of
     that script at all.</p>
 
+   <p>Letter-spacing ignores zero-width characters (such as those from the
+    Unicode Cf category). For example, &lsquo;<a
+    href="#letter-spacing0"><code
+    class=property>letter-spacing</code></a>&rsquo; applied to
+    <code>A&amp;zwsp;B</code> is identical to <code>AB</code>.
+
    <p>When the resulting space between two characters is not the same as the
     default space, user agents should not use optional ligatures.</p>
 

css3-text/Overview.src.html

@@ -377,7 +377,7 @@ <h2 id="white-space-processing">
     <a href="http://www.w3.org/TR/CSS21/visuren.html#anonymous">9.2.2.1</a></p>
 
   <p>Control characters (Unicode class Cc) other than tab (U+0009), line feed
-    (U+000A), space (U+0020), and the bidi formatting characters (U+202<var>x</var>)
+    (U+000A), and carriage return (U+000D)
     are ignored for the purpose of rendering.
 
   <h3 id="white-space-collapsing">
@@ -2082,6 +2082,10 @@ <h3 id="letter-spacing">
       the cursive connections, it should not apply letter-spacing between
       characters of that script at all.</p>
 
+    <p>Letter-spacing ignores zero-width characters (such as those from the
+      Unicode Cf category). For example, 'letter-spacing' applied to
+      <code>A&amp;zwsp;B</code> is identical to <code>AB</code>.
+
     <p>When the resulting space between two characters is not the same as the
       default space, user agents should not use optional ligatures.</p>