[css-contain] Editorial / obvious bugfix improvements to style scoping

Part of #2349

css-contain-1/Overview.bs

@@ -260,7 +260,8 @@ Style Containment</h3>
 	Note: [[CSS-REGIONS-1]] has normative requirements on how <a>style containment</a> affects regions.
 
 	A <dfn export for=property lt="scoped | scoped property | scoped properties">scoped property</dfn> has its effects scoped to a particular element or subtree.
-	It must act as if the scoping element was the root of the document
+	If scoped to an element,
+	it must act as if the scoping element was the root of the document
 	for the purpose of evaluating the property's effects:
 	any uses of the property outside the scoping element must have no effect on the uses of the property on or in the scoping element,
 	and vice versa.
@@ -271,7 +272,7 @@ Style Containment</h3>
 	When scoped, the 'counter-set' and 'counter-increment' <a spec=css-lists-3>create a new counter</a>.
 
 	<div class=example>
-	If 'counter-increment' is scoped to an element,
+	If 'counter-increment' is scoped to an element's subtree,
 	the first use of it within the subtree acts as if the named counter were set to 0 at the scoping element,
 	regardless of whether the counter had been used outside the scoping element.
 	Any increments made within the subtree have no effect on counters of the same name outside the scoping element.

css-contain-1/issues-2017-cr.html

@@ -100,6 +100,13 @@ <h1>CSS Contain Level 1 Disposition of Comments for 2017-02-21 WD</h1>
 Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-377214307'>https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-377214307</a>
 Response: <a href='https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-379124749'>https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-379124749</a>
 Open</pre>
+<pre class=' open' id='issue-9'>
+Issue 9. <a href='#issue-9'>#</a>
+Summary:  Clarify style containment property scopment
+From:     Oriol Brufau
+Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/2349'>https://github.com/w3c/csswg-drafts/issues/2349</a>
+Response: <a href='https://github.com/w3c/csswg-drafts/issues/2349#issuecomment-379127071'>https://github.com/w3c/csswg-drafts/issues/2349#issuecomment-379127071</a>
+Open</pre>
 <script>
 (function () {
     var sheet = document.styleSheets[0];

css-contain-1/issues-2017-cr.txt

@@ -70,3 +70,10 @@ Comment:  https://github.com/w3c/csswg-drafts/issues/2483
 Comment:  https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-377214307
 Response: https://github.com/w3c/csswg-drafts/issues/2483#issuecomment-379124749
 Open
+----
+Issue 9.
+Summary:  Clarify style containment property scopment
+From:     Oriol Brufau
+Comment:  https://github.com/w3c/csswg-drafts/issues/2349
+Response: https://github.com/w3c/csswg-drafts/issues/2349#issuecomment-379127071
+Open