[css-text-3] Trim ideographic spaces at the end of a line, to properly handle typical CJK typesetting. #2500

Author: fantasai

css-text-3/Overview.bs

@@ -756,15 +756,19 @@ Characters and Letters</h3>
         <dfn lt="tab stop">Tab stops</dfn> occur at points that are multiples of the tab size
         from the block's starting content edge.
         The tab size is given by the 'tab-size' property.
-      <li>A sequence of <a>collapsible</a> spaces at the end of a line
+      <li>A sequence at the end of a line
         (ignoring any intervening <a>inline box</a> boundaries)
+        of <a>collapsible</a> spaces (U+0020)
+        and/or ideographic spaces (U+3000) whose 'white-space' value collapses spaces
         is removed.
-      <li>If spaces or tabs at the end of a line are non-collapsible
+      <li>If there remains any sequence of <a>white space</a>
+        and/or ideographic spaces (U+3000)
+        at the end of a line:
         <ul>
           <li>If 'white-space' is set to ''pre-wrap'',
-             the UA must either <a>hang</a> the <a>white space</a>
+             the UA must either <a>hang</a> this sequence
              or visually collapse the character advance widths
-             of any overflowing spaces
+             of any that overflow
              such that they don't take up space in the line.
 
              Note: Hanging the white space rather than collapsing it