Source the SharedDictionary correctly

Author: donokuda

src/GitHub.VisualStudio/Styles/GitHubComboBox.xaml

@@ -1,6 +1,11 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:cache="clr-namespace:GitHub.VisualStudio.Helpers"
                     xmlns:ui="clr-namespace:GitHub.UI;assembly=GitHub.UI">
+
+    <ResourceDictionary.MergedDictionaries>
+        <cache:SharedDictionaryManager Source="pack://application:,,,/GitHub.UI;component/SharedDictionary.xaml" />
+    </ResourceDictionary.MergedDictionaries>
 
     <Style x:Key="GitHubComboBoxBorder" TargetType="{x:Type Border}">
         <Setter Property="Margin" Value="10" />
@@ -25,7 +30,6 @@
                 <Setter Property="Foreground" Value="{DynamicResource GitHubVsToolWindowText}" />
             </Style>
 
-            
             <Style TargetType="{x:Type Separator}" BasedOn="{StaticResource {x:Type Separator}}">
                 <Setter Property="Background" Value="{DynamicResource GitHubComboBoxBorderBrush}" />
                 <Setter Property="Margin" Value="0" />