[selectors] Fix more issues from Anne.

Author: tabatkins

selectors/Overview.bs

@@ -572,14 +572,12 @@ Evaluating a Selector</h3>
 
 	This section describes how to <dfn export>evaluate a selector</dfn> against a set of elements.
 
-	APIs using this algorithm must provide a selector.
+	APIs using this algorithm must provide a selector,
+	and one or more <a>element tree</a> root elements
+	indicating the trees that will be searched by the selector.
 	They may optionally provide:
 
 	<ul>
-		<li>
-			a <a>selector match list</a> of elements to match against.
-			If not specified, the <a>initial selector match list</a> for the selector's context is used.
-
 		<li>
 			a <a>scoping method</a> and <a>scoping root</a>.
 			If not specified, the selector defaults to being unscoped.
@@ -603,9 +601,12 @@ Evaluating a Selector</h3>
 			If not specified, this defaults to allowing all pseudo-elements.
 	</ul>
 
-	A <a>selector</a> is evaluated against some initial list of elements,
-	as determined by the context that the selector is evaluated in:
+	A <a>selector</a> is evaluated against some initial list of elements:
 	the <dfn export>selector match list</dfn>.
+	The <a>selector match list</a> is initially populated with the <a>element tree</a> roots
+	provided to the algorithm,
+	and all elements reachable from them by traversing any number of child lists.
+
 	If the selector is <a>scope-contained</a>,
 	the <a>selector match list</a> is immediately filtered
 	to contain only elements that are either the <a>scoping root</a>
@@ -656,15 +657,6 @@ Evaluating a Selector</h3>
 	as long as it results in the same elements being returned
 	as the spec's algorithm would.
 
-	Each context that a selector can be evaluated in
-	must define the <dfn export>initial selector match list</dfn>,
-	the list of elements that every selector in that context begins with.
-
-	When evaluating a selector against a DOM document,
-	the <a>initial selector match list</a>
-	is the root element and all of its descendants,
-	ordered by a pre-order traversal.
-
 	Issue: The relative position of pseudo-elements in the <a>selector match list</a> is undefined.
 	There's not yet a context that exposes this information,
 	but we need to decide on something eventually,
@@ -674,8 +666,9 @@ Evaluating a Selector</h3>
 <h3 id='data-model'>
 Data Model</h3>
 
-	Selectors are matched against a <a>selector match list</a> of elements,
-	which is usually arranged in an abstract tree structure.
+	Selectors are matched against an <dfn export>element tree</dfn>,
+	which is an abstract tree structure containing elements
+	having the structure defined in the <a href="http://dom.spec.whatwg.org/#trees">DOM Standard</a> [[!DOM]].
 
 	Each element may have any of:
 
@@ -708,13 +701,13 @@ Data Model</h3>
 	and can't be matched by <em>any</em> <a>pseudo-class</a> except for '':host'' and '':host-context()''.)
 
 	In a DOM document,
-	the DOM is used as the <a>selector match list</a>.
-	Each DOM element is an element in the <a>selector match list</a>,
-	with the DOM element's tagname as the type,
+	the DOM is used as the <a>element tree</a>.
+	Each DOM element is an element in the <a>element tree</a>,
+	with the DOM element's namespace and local name as the type,
 	and its ID, class list, attributes, and child elements
-	as the ID, classes, attributes, and child elements in the <a>selector match list</a>.
+	as the ID, classes, attributes, and child elements in the <a>element tree</a>.
 	The rest of the information in the DOM is also accessible
-	as the arbitrary additional information in the <a>selector match list</a>.
+	as the arbitrary additional information in the <a>element tree</a>.
 
 
 <h3 id="scoping">
@@ -2147,7 +2140,7 @@ User Action Pseudo-classes</h2>
 	Note: The specifics of hit-testing,
 	necessary to know when several of the pseudo-classes defined in this section apply,
 	are not yet defined,
-	but should be in the future.
+	but will be in the future.
 
 <h3 id="the-hover-pseudo">
 The pointer hover pseudo-class '':hover''</h3>