[css-text-3] Adjust timing of text transform

text-transform should happen after white-space collapsing but before
Trimming and Positioning.

Closes #4254

Author: frivoal

css-text-3/Overview.bs

@@ -616,8 +616,9 @@ Text Processing</h3>
       text-transform/text-transform-multiple-001.html
     </wpt>
 
-    <p>Text transformation happens after <a href="#white-space-rules">white
-      space processing</a>, which means that ''full-width'' only transforms
+    <p>Text transformation happens after [[#white-space-phase-1]]
+      but before [[#white-space-phase-2]].
+      This means that ''full-width'' only transforms
       U+0020 spaces to U+3000 within <a>preserved</a> white space.
 
       <wpt>