DevTools: do not lazy load provided view if it was explicitly added.

third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js

Index: third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js b/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
index 15604bee6d14ab7d1805ad9885760e330385c076..d16d294c3ee80bd85af3d0dbea7ef9899c8c9741 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
@@ -1377,6 +1377,9 @@ WebInspector.ExtensibleTabbedPaneController.prototype = {
     _tabSelected: function(event)
     {
         var tabId = /** @type {string} */ (event.data.tabId);
+        if (!this._extensions.has(tabId))
+            return;
+
         this._viewForId(tabId);
 
         var descriptor = this._extensions.get(tabId).descriptor();