[css-cascade] Remove mention of the Override origin, per CSSWG resolution. Fixes #1385.

Author: tabatkins

css-cascade-3/Overview.bs

@@ -630,10 +630,8 @@ Cascading</h2>
 				<li>Transition declarations [[!CSS3-TRANSITIONS]]
 				<li>Important user agent declarations
 				<li>Important user declarations
-				<li>Important override declarations [[!DOM-LEVEL-2-STYLE]]
 				<li>Important author declarations
 				<li>Animation declarations [[!CSS3-ANIMATIONS]]
-				<li>Normal override declarations [[!DOM-LEVEL-2-STYLE]]
 				<li>Normal author declarations
 				<li>Normal user declarations
 				<li>Normal user agent declarations
@@ -708,11 +706,6 @@ Cascading Origins</h3>
 	Extensions to CSS define the following additional <a>origins</a>:
 
 	<dl>
-		<dt id='cascade-origin-override'>Override
-		<dd>
-			DOM Level 2 Style [[!DOM-LEVEL-2-STYLE]] defines an interface for “override” styles,
-			which enter the cascade at a higher level than other author rules.
-
 		<dt id='cascade-origin-animation'>Animation
 		<dd>
 			CSS Animations [[CSS3-ANIMATIONS]] generate “virtual” rules representing their effects when running.

css-cascade-4/Overview.bs

@@ -737,10 +737,8 @@ Cascading</h2>
 				<li>Transition declarations [[!CSS3-TRANSITIONS]]
 				<li>Important user agent declarations
 				<li>Important user declarations
-				<li>Important override declarations [[!DOM-LEVEL-2-STYLE]]
 				<li>Important author declarations
 				<li>Animation declarations [[!CSS3-ANIMATIONS]]
-				<li>Normal override declarations [[!DOM-LEVEL-2-STYLE]]
 				<li>Normal author declarations
 				<li>Normal user declarations
 				<li>Normal user agent declarations
@@ -842,11 +840,6 @@ Cascading Origins</h3>
 	Extensions to CSS define the following additional <a>origins</a>:
 
 	<dl>
-		<dt><dfn export id='cascade-origin-override'>Override Origin</dfn>
-		<dd>
-			DOM Level 2 Style [[!DOM-LEVEL-2-STYLE]] defines an interface for “override” styles,
-			which enter the cascade at a higher level than other author rules.
-
 		<dt><dfn export id='cascade-origin-animation'>Animation Origin</dfn>
 		<dd>
 			CSS Animations [[CSS3-ANIMATIONS]] generate “virtual” rules representing their effects when running.
@@ -1022,7 +1015,7 @@ Rolling Back The Cascade: the ''revert'' keyword</h4>
 		<dd>
 			Rolls back the <a>cascaded value</a> to the user level,
 			so that the <a>specified value</a> is calculated as if no author-level rules were specified for this property on this element.
-			For the purpose of ''revert'', this origin includes the Override and Animation <a>origins</a>.
+			For the purpose of ''revert'', this origin includes the Animation <a>origin</a>.
 	</dl>
 
 <h2 id="changes">