html: stop at scope marker node when generating implied </a> tags

A <a> tag generates implied end tags for any open <a> elements.
But it shouldn't do that when it is inside a table cell the the open <a>
is outside the table.
So stop the search for an open <a> when we reach a scope marker node.

Pass tests1.dat, test 78:
<a href="blah">aba<table><tr><td><a href="foo">br</td></tr>x</table>aoe

| <html>
|   <head>
|   <body>
|     <a>
|       href="blah"
|       "abax"
|       <table>
|         <tbody>
|           <tr>
|             <td>
|               <a>
|                 href="foo"
|                 "br"
|       "aoe"

Also pass test 79:
<table><a href="blah">aba<tr><td><a href="foo">br</td></tr>x</table>aoe

3 files changed