[css-contain-2][editorial] Move the 'possible optimizations' to non-normative subsections

Author: tabatkins

css-contain-2/Overview.bs

@@ -700,6 +700,12 @@ Size Containment</h3>
 		and its [=natural height=] is treated as 0.
 	</div>
 
+
+<h4 id='containment-size-opt' class="no-toc">
+Possible Size-Containment Optimizations</h4>
+
+	<em>This section is non-normative.</em>
+
 	By itself, <a>size containment</a> does not offer much optimization opportunity.
 	Its primary benefit on its own is that tools which want to lay out the [=size containment box|containment box=]'s contents
 	based on the [=size containment box|containment box=]'s size
@@ -880,6 +886,11 @@ Layout Containment</h3>
 		contain-layout-baseline-005.html
 		</wpt>
 
+<h4 id='containment-layout-opt' class="no-toc">
+Possible Layout-Containment Optimizations</h4>
+
+	<em>This section is non-normative.</em>
+
 	Possible optimizations that can be enabled by <a>layout containment</a> include (but are not limited to):
 
 	1. When laying out the page,
@@ -990,6 +1001,13 @@ Style Containment</h3>
 	</code></pre>
 	</div>
 
+
+
+<h4 id='containment-style-opt' class="no-toc">
+Possible Style-Containment Optimizations</h4>
+
+	<em>This section is non-normative.</em>
+
 	Possible optimizations that can be enabled by <a>style containment</a> include (but are not limited to):
 
 	1. Whenever a property is changed on a descendant of an element with [=style containment=],
@@ -1093,7 +1111,11 @@ Paint Containment</h3>
 	contain-paint-baseline-001.html
 	</wpt>
 
-<div class=informative>
+<h4 id='containment-paint-opt' class="no-toc">
+Possible Paint-Containment Optimizations</h4>
+
+	<em>This section is non-normative.</em>
+
 	Possible optimizations that can be enabled by <a>paint containment</a> include (but are not limited to):
 
 	1. If the [=paint containment box|containment box=] is off-screen or obscured,
@@ -1111,7 +1133,6 @@ Paint Containment</h3>
 
 	3. Because they are guaranteed to be stacking contexts,
 		scrolling elements can be painted into a single GPU layer.
-</div>
 
 Suppressing An Element's Contents Entirely: the 'content-visibility' property {#content-visibility}
 =================