[Switch Access] Always identify the onscreen keyboard

This change checks if the node is a keyboard before checking if it's
a window, fixing the attached bugs.

AX-Relnotes: n/a.
Bug: 1120730, 1120734
Change-Id: I57fe00ec8c805bb887ed67a743cf8181cf1291cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2369612
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: Abigail Klein <abigailbklein@google.com>
Cr-Commit-Position: refs/heads/master@{#801235}

chrome/browser/resources/chromeos/accessibility/switch_access/nodes/node_wrapper.js

@@ -356,12 +356,12 @@ class RootNodeWrapper extends SARootNode {
    * @return {!RootNodeWrapper}
    */
   static buildTree(rootNode) {
-    if (SwitchAccessPredicate.isWindow(rootNode)) {
-      return WindowRootNode.buildTree(rootNode);
-    }
     if (rootNode.role === chrome.automation.RoleType.KEYBOARD) {
       return KeyboardRootNode.buildTree();
     }
+    if (SwitchAccessPredicate.isWindow(rootNode)) {
+      return WindowRootNode.buildTree(rootNode);
+    }
 
     const root = new RootNodeWrapper(rootNode);
     const childConstructor = (node) => NodeWrapper.create(node, root);