[css-text-decor] Composit text+decor before shadowing? Experimental edit.

--HG--
extra : rebase_source : a09d7d391dc46a19474e5b512d9fc599e3baa266

Author: fantasai

css-text-decor/Overview.html

@@ -1692,15 +1692,9 @@ <h2 id=text-shadow-property><span class=secno>4. </span> Text Shadows: the
    class=property>box-shadow</code>’</a> <a href="#CSS3BG"
    rel=biblioentry>[CSS3BG]<!--{{!CSS3BG}}--></a>. (But note that spread
    values and the ‘<code class=css>inset</code>’ keyword are not
-   allowed.) The shadow is applied to all of the element's text as well as
-   any text decorations it specifies.
-
-  <p>If the color of the shadow is not specified, the shadow has the color of
-   the ink it shadows; that is, it matches the ‘<code
-   class=property>color</code>’ property when shadowing text, and the ‘<a
-   href="#text-decoration-color"><code
-   class=property>text-decoration-color</code></a>’ property when shadowing
-   text decorations.
+   allowed.) Each layer shadows the element's text and all its text
+   decorations (composited together). If the color of the shadow is not
+   specified, the shadow has the resulting color of the ink that it shadows.
 
   <p>The shadow effects are applied front-to-back: the first shadow is on
    top. The shadows may thus overlay each other, but they never overlay the

css-text-decor/Overview.src.html

@@ -1153,13 +1153,10 @@ <h2 id="text-shadow-property">
     <a href="http://www.w3.org/TR/css3-background/#the-box-shadow">'box-shadow'</a>
     [[!CSS3BG]].
     (But note that spread values and the ''inset'' keyword are not allowed.)
-    The shadow is applied to all of the element's text as well as any
-    text decorations it specifies.
-
-  <p>If the color of the shadow is not specified,
-    the shadow has the color of the ink it shadows;
-    that is, it matches the 'color' property when shadowing text,
-    and the 'text-decoration-color' property when shadowing text decorations.
+    Each layer shadows the element's text and all its text decorations
+    (composited together).
+    If the color of the shadow is not specified,
+    the shadow has the resulting color of the ink that it shadows.
 
   <p>The shadow effects are applied front-to-back: the first shadow is on
     top. The shadows may thus overlay each other, but they never overlay