[css3-cascade] Make it clearer how origin affects the cascade.

Author: tabatkins

css3-cascade/Overview.html

@@ -488,6 +488,9 @@ <h3 id=cascade><span class=secno>4.2. </span> Cascading Declarations</h3>
      <li>Normal user agent declarations
     </ol>
 
+    <p> Declarations from origins earlier in this list win over declarations
+     from later origins.
+
    <dt>Scope
 
    <dd> If a declaration belongs to a ruleset with a <a

css3-cascade/Overview.src.html

@@ -305,6 +305,9 @@ <h3 id='cascade'>
 				<li>Normal user agent declarations
 			</ol>
 
+			<p>
+				Declarations from origins earlier in this list win over declarations from later origins.
+
 		<dt>Scope
 		<dd>
 			If a declaration belongs to a ruleset with a <a href="http://www.w3.org/TR/selectors4/#scoping">scoped selector</a>,