[DevTools] Add preferred size to WebInspector.View.

Source/devtools/front_end/TabbedPane.js

Index: Source/devtools/front_end/TabbedPane.js
diff --git a/Source/devtools/front_end/TabbedPane.js b/Source/devtools/front_end/TabbedPane.js
index 3a93bafe529048e3a3e2339f608ae8336149291b..f8716afc99852607349a02a1102877703d8a5303 100644
--- a/Source/devtools/front_end/TabbedPane.js
+++ b/Source/devtools/front_end/TabbedPane.js
@@ -385,10 +385,12 @@ WebInspector.TabbedPane.prototype = {
     calculateMinimumSize: function()
     {
         var size = WebInspector.VBox.prototype.calculateMinimumSize.call(this);
+        var minContentSize = new Size(0, 0, 50, 50);
+        size = size.widthToMax(minContentSize).heightToMax(minContentSize);
         if (this._verticalTabLayout)
-            size.width += this._headerElement.offsetWidth;
+            size = size.addWidth(new Size(this._headerElement.offsetWidth, 0));
         else
-            size.height += this._headerElement.offsetHeight;
+            size = size.addHeight(new Size(0, this._headerElement.offsetHeight));
         return size;
     },