Bug 1345997 - Add a check for the inspector toolbox when checking if the grid inspector or box model is visible. r=jdescottes

MozReview-Commit-ID: 5Ve2COO5Vkc

devtools/client/inspector/boxmodel/box-model.js

@@ -78,8 +78,8 @@ BoxModel.prototype = {
    * Returns true if the computed or layout panel is visible, and false otherwise.
    */
   isPanelVisible() {
-    return this.inspector.toolbox.currentToolId === "inspector" &&
-           this.inspector.sidebar &&
+    return this.inspector.toolbox && this.inspector.sidebar &&
+           this.inspector.toolbox.currentToolId === "inspector" &&
            (this.inspector.sidebar.getCurrentTabID() === "layoutview" ||
             this.inspector.sidebar.getCurrentTabID() === "computedview");
   },

devtools/client/inspector/grids/grid-inspector.js

@@ -201,8 +201,8 @@ GridInspector.prototype = {
    * Returns true if the layout panel is visible, and false otherwise.
    */
   isPanelVisible() {
-    return this.inspector.toolbox.currentToolId === "inspector" &&
-           this.inspector.sidebar &&
+    return this.inspector.toolbox && this.inspector.sidebar &&
+           this.inspector.toolbox.currentToolId === "inspector" &&
            this.inspector.sidebar.getCurrentTabID() === "layoutview";
   },