Specify br and wbr rendering as magic

Closes #2291.

Author: domenic

source

@@ -109358,9 +109358,8 @@ del, s, strike { text-decoration: line-through; }
 q::before { content: open-quote; }
 q::after { content: close-quote; }
 
-<span data-x="" id="br-wbr-content">br { display-outside: newline; } /* <a href="#bidi-rendering">this also has bidi implications</a> */
+<span data-x="" id="br-wbr-content">
 nobr { white-space: nowrap; }
-wbr { display-outside: break-opportunity; } /* <a href="#bidi-rendering">this also has bidi implications</a> */
 nobr wbr { white-space: normal; }</span></pre>
 
   <p>The following rules are also expected to apply, as
@@ -109525,6 +109524,22 @@ br[clear=all i], br[clear=both i] { clear: both; }</pre>
 
   </ol>
 
+  <hr>
+
+  <p>The <code>br</code> element is expected to render as a forced line (and bidi paragraph) break,
+  ignoring the effect of the <span>'white-space'</span> property.</p>
+
+  <p>The <code>wbr</code> element is expected to render as a line break opportunity.</p>
+
+  <p>Most CSS properties do not affect the rendering of these elements; however, some such as
+  <span>'line-height'</span> and <span>'font-size'</span> seem to do so under some circumstances.
+  The exact specification for which properties apply, and when, is still being determined.</p>
+
+
+  <h4>The <code>button</code> element</h4>
+
+  <p>The <code>button</code> element is expected to render as an <span>'inline-block'</span> box
+  depicting a button whose contents are the contents of the element.</p>
 
   <h4 id="bidi-rendering">Bidirectional text</h4>
 
@@ -109547,9 +109562,7 @@ input[dir=auto i]:matches([type=search i], [type=tel i], [type=url i],
 [type=email i]), textarea[dir=auto i], pre[dir=auto i] {
   unicode-bidi: plaintext;
 }
-/* see prose for input elements whose type attribute is in the Text state */
-
-/* the <a href="#br-wbr-content">rules setting the 'content' property</a> on <code>br</code> and <code>wbr</code> elements also has bidi implications */</pre>
+/* see prose for input elements whose type attribute is in the Text state */</pre>
 
   <p>When an <code>input</code> element's <code data-x="attr-dir">dir</code> attribute is in the
   <span data-x="attr-dir-auto">auto</span> state and its <code data-x="attr-input-type">type</code>