[Devtools] Do not switch tabs by default when adding a tab.

Source/devtools/front_end/timeline/TimelinePanel.js

Index: Source/devtools/front_end/timeline/TimelinePanel.js
diff --git a/Source/devtools/front_end/timeline/TimelinePanel.js b/Source/devtools/front_end/timeline/TimelinePanel.js
index 3123606d92cfc4857d6b5e4f98fb39212ac44ef6..b61a44c6365227fcd47883b68efb69421e1404a6 100644
--- a/Source/devtools/front_end/timeline/TimelinePanel.js
+++ b/Source/devtools/front_end/timeline/TimelinePanel.js
@@ -1172,7 +1172,7 @@ WebInspector.TimelineDetailsView.prototype = {
     appendTab: function(id, tabTitle, view, tabTooltip, userGesture, isCloseable)
     {
         WebInspector.TabbedPane.prototype.appendTab.call(this, id, tabTitle, view, tabTooltip);
-        if (this._lastUserSelectedTabId !== this.selectedTabId)
+        if (this._lastUserSelectedTabId && this._lastUserSelectedTabId !== this.selectedTabId)

[pfeldman, 2014/10/06 04:56:14]

Is (was) this showing all the tabs as they were added? I wonder if we should
turn the control flow the other way around so that this details view was
listening to the timeline selection and was updating itself. That way it can
manage the tab selection properly.

The way it is now is because this details view was created out of the popover
that used to show upon timeline hover. Hence the suboptimal way of living.

@pdr: you don't have to do this, we can arrange this for you!

             this.selectTab(id);
     },