test(chrome): compare checked, selected and focused across both producers

the target enumeration carries none of the three, so they reach a spec
through the ax handle alone, and a selector naming one of them resolves
against that same reading. the shadow fixture holds the focused control
inside its shadow root, where document.activeElement names the mount
element and only a producer that descends finds the field.

internal/driver/chrome/testdata/fact-parity-shadow.html

@@ -27,9 +27,19 @@
           <button id="shadow-cancel" disabled>cancel</button>
           <input id="shadow-amount" type="text" value="10" placeholder="0.00" />
           <input id="shadow-password" type="password" placeholder="Password" />
+          <input id="shadow-agree" type="checkbox" />
+          <select id="shadow-choice">
+            <option id="shadow-choice-first">first</option>
+          </select>
           <div id="shadow-plain">plain</div>
         </div>
         <div id="shadow-scroller"><div id="shadow-scroller-content"></div></div>`;
+      // document.activeElement names the HOST while focus is inside its shadow
+      // root, so a producer that does not descend reports focus on the mount
+      // element and never on the control, which is what a Compose for Web page
+      // looks like from the outside.
+      root.getElementById("shadow-agree").checked = true;
+      root.getElementById("shadow-save").focus();
     </script>
   </body>
 </html>

internal/driver/chrome/testdata/fact-parity.html

@@ -97,6 +97,14 @@
     <div id="filler"></div>
     <script id="page-script">
       document.getElementById("delegating-root").onclick = function () {};
+      // checked and focused are live state: the markup attribute records only
+      // what the page loaded with, and nothing writes focus down at all. Both
+      // producers read them off the element, so the fixture has to hold one of
+      // each or the comparison is false against false over the whole page.
+      // #choice-first is the third: an option a select made current with no
+      // attribute anywhere saying so.
+      document.getElementById("agree").checked = true;
+      document.getElementById("save").focus();
     </script>
   </body>
 </html>