Bug 1249119 - Prevent exception when opening inspector on a loading document. r=pbro

MozReview-Commit-ID: 9TNRUblT0SW

--HG--
extra : rebase_source : c8c30017cf5cb5be947a5edd5ff48908e0bf2db4

devtools/client/inspector/markup/views/markup-container.js

@@ -633,8 +633,10 @@ MarkupContainer.prototype = {
     // Markup tree item should have accessible selected state.
     this.tagLine.setAttribute("aria-selected", value);
     if (this._selected) {
-      this.markup.getContainer(this.markup._rootNode).elt.setAttribute(
+      let container = this.markup.getContainer(this.markup._rootNode);
-        "aria-activedescendant", this.id);
+      if (container) {
+        container.elt.setAttribute("aria-activedescendant", this.id);
+      }
       this.tagLine.setAttribute("selected", "");
       this.tagState.classList.add("theme-selected");
     } else {

devtools/server/actors/inspector.js

@@ -618,6 +618,9 @@ var NodeActor = exports.NodeActor = protocol.ActorClassWithSpec(nodeSpec, {
    * Get a unique selector string for this node.
    */
   getUniqueSelector: function () {
+    if (Cu.isDeadWrapper(this.rawNode)) {
+      return "";
+    }
     return CssLogic.findCssSelector(this.rawNode);
   },