[css-contain][css-content] Clarify effects of style containement

The less mature spec (css-content) should be the one defining
how it interacts with the more mature mechanism (css-contain).
Moving existing descriptions from css-contain to css-content

Also, 'break-inside' was implied by "the break-* properties",
when only 'break-before' and 'break-after' were intended.

This is part of #1872

Author: frivoal

css-contain-1/Overview.bs

@@ -13,9 +13,13 @@ Editor: Tab Atkins, Google, http://xanthir.com/contact/, w3cid 42199
 Editor: Florian Rivoal, On behalf of Bloomberg, https://florian.rivoal.net/, w3cid 43241
 Abstract: This CSS module describes the 'contain' property, which indicates that the element's subtree is independent of the rest of the page. This enables heavy optimizations by user agents when used well.
 Ignored Terms: scrollWidth, scrollHeight, clientWidth, clientHeight, formatting context
-Link Defaults: css-lists-3 (property) counter-increment, css-content-3 (property) string-set
+Link Defaults: css-lists-3 (property) counter-increment
+</pre>
+<pre class="anchors">
+spec: css2; urlPrefix: https://www.w3.org/TR/CSS2/
+	type: property; url: generate.html#propdef-content; text: content
+	type: value; for: content; url: generate.html#value-def-open-quote;; text: open-quote
 </pre>
-
 <h2 id='intro'>
 Introduction</h2>
 
@@ -150,6 +154,11 @@ Types of Containment</h2>
 	and helps authors compose their page out of functional units,
 	as it limits how widely an effect a given change can have on a document.
 
+	Advisement: Specification authors introducing new properties or mechanisms
+	need to consider whether and how the various types of containment
+	affect what they are introducing,
+	and include in their specification any effect not described here.
+
 <h3 id='containment-size'>
 Size Containment</h3>
 
@@ -254,11 +263,10 @@ Style Containment</h3>
 
 	1. The following properties must have no effect on descendants of the element:
 
-		* 'break-*' (and the related aliases)
-		* 'bookmark-*'
-		* 'string-set'
+		* 'break-before' and 'break-after' (and the related aliases)
 
-	2. The 'counter-increment', 'counter-set', 'flow-from', 'flow-into', and 'content' (for the purpose of ''content/open-quote''/etc values) properties must be <a>scoped</a> to the element's sub-tree.
+	2. The 'counter-increment', 'counter-set', 'flow-from', 'flow-into', and <a property spec=css2>content</a> (for the purpose of ''content/open-quote''/etc values) properties
+	    must be <a>scoped</a> to the element's sub-tree.
 
 	A <dfn export local-lt="scoped">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
@@ -399,7 +407,7 @@ Answers are provided below.
 <dd>No.
 </dl>
 
-<h2 class="no-num" id="changes">Appendix A. Changes</h2>
+<h2 class="no-num non-normative" id="changes">Appendix A. Changes</h2>
 
 This appendix is <em>informative</em>.
 
@@ -410,6 +418,9 @@ This appendix is <em>informative</em>.
 	<li>Move the definition of "Becoming a formatting context" back to this specification
 	<li>Rename "Becoming a formatting context" to "Becoming a formatting context root".
 	<li>Clarify to which box paint containment clips.
+	<li>Move the interaction between containment and the <code>bookmark-*</code> and <code>string-set</code> properties to  [[CSS-CONTENT-3]]
+	<li>Explicitly expnd <code>break-*</code> to </code>break-before</code> and <code>break-after</code>
+	    to avoid implying that <code>break-inside</code> is affected by style containment.
 </ul>
 
 <h3 id="2017-04-19-changes">Changes from the

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

@@ -64,11 +64,18 @@ <h1>CSS Contain Level 1 Disposition of Comments for 2017-02-21 WD</h1>
 <pre class='a' id='issue-4'>
 Issue 4. <a href='#issue-4'>#</a>
 Summary:  To which box does paint containment clip?
-From:     Orio Brufau
+From:     Oriol Brufau
 Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/1809'>https://github.com/w3c/csswg-drafts/issues/1809</a>
 Response: <a href='https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088'>https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088</a>
 Closed:   Accepted
 Resolved: <a href='https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088'>https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088</a></pre>
+<pre class=' open' id='issue-5'>
+Issue 5. <a href='#issue-5'>#</a>
+Summary:  Clarify effects of style containment
+From      Oriol Brufau
+Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/1872'>https://github.com/w3c/csswg-drafts/issues/1872</a>
+Response: <a href='https://github.com/w3c/csswg-drafts/issues/1872#issuecomment-342334343'>https://github.com/w3c/csswg-drafts/issues/1872#issuecomment-342334343</a>
+Open</pre>
 <script>
 (function () {
     var sheet = document.styleSheets[0];

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

@@ -34,8 +34,15 @@ Verified: https://github.com/w3c/csswg-drafts/issues/1791#issuecomment-331636396
 ----
 Issue 4.
 Summary:  To which box does paint containment clip?
-From:     Orio Brufau
+From:     Oriol Brufau
 Comment:  https://github.com/w3c/csswg-drafts/issues/1809
 Response: https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088
 Closed:   Accepted
 Resolved: https://github.com/w3c/csswg-drafts/issues/1809#issuecomment-342333088
+----
+Issue 5.
+Summary:  Clarify effects of style containment
+From      Oriol Brufau
+Comment:  https://github.com/w3c/csswg-drafts/issues/1872
+Response: https://github.com/w3c/csswg-drafts/issues/1872#issuecomment-342334343
+Open

css-content-3/Overview.bs

@@ -971,6 +971,8 @@ The string-set property</h4>
 	</dl>
 
 <!--end of insert from GCPM3 -->
+	If an element has <a>style containment</a>,
+	the 'string-set' property must have no effects on descendants of that element.
 
 
 	<div class="example">
@@ -1169,6 +1171,10 @@ Bookmarks</h2>
 	exactly as if navigating to that element by fragment URL.
 	<span class="note">This will also trigger matching the '':target'' pseudo-class.</span>
 
+	If an element has <a>style containement</a>, the
+	'bookmark-level', 'bookmark-label', and 'bookmark-state' properties
+	must have no effect on descendants of the element.
+
 <h3 id="bookmark-level">
 bookmark-level
 </h3>
@@ -1318,6 +1324,9 @@ bookmark-state</h3>
 
 	* Dave Cramer added as co-editor. Ian Hickson and Håkon Wium Lie are now former editors.
 
+	* Moved effects of style containement on properties of this specification from the css-contain specification to this one,
+	    due to their respective maturity.
+
 <h2 class="no-num" id="acknowledgements">Acknowledgements</h2>
 
 	Stuart Ballard,