DevTools: Introduce Landing page for Timeline panel.

third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css

Index: third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css b/third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css
index 2d72edb4c118efc91346fa4eb0f428c619db6496..ee8aacf8351321170c3b3c208661887d3f70277b 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css
+++ b/third_party/WebKit/Source/devtools/front_end/ui/tabbedPane.css
@@ -269,6 +269,15 @@
     background-color: transparent;
 }
 
+.tabbed-pane-no-tab-borders .tabbed-pane-header-tab {
+    border: none;
+    padding: 2px 10px;
+}
+
+.tabbed-pane-no-tab-borders .tabbed-pane-header-contents {
+    margin-left: 0;
+}
+
 .tabbed-pane-left-toolbar {
     margin-right: -4px;
     flex: none;