Split out common code into subtree and update with latest changes

Build/Common.Build.CSharp.targets

@@ -6,7 +6,7 @@
   <PropertyGroup Condition="$(SuppressCommonAssemblyVersion)">
     <DefineConstants>$(DefineConstants);SUPPRESS_COMMON_ASSEMBLY_VERSION</DefineConstants>
   </PropertyGroup>
-  
+
   <!--
   Returns the paths and names required for generating a vsixmanifest file.
   The default targets for this occasionally return the wrong files depending
@@ -28,7 +28,7 @@
   <!--
   Transforms our ConditionalEmbeddedResource into EmbeddedResource item
   groups with textual replacements in the .resx file.
-  
+
   Currently the search and replace just updates the VS target version and
   the build root.
     -->
@@ -42,7 +42,7 @@
       Overwrite="true"/>
 
     <Message Text="Written to @(ConditionalEmbeddedResource->'$(IntermediateOutputPath)%(Filename).xform.resx')" Importance="normal" />
-    
+
     <ItemGroup>
       <FileWrites Include="@(ConditionalEmbeddedResource->'$(IntermediateOutputPath)%(Filename).xform.resx')" />
       <EmbeddedResource Include="@(ConditionalEmbeddedResource->'$(IntermediateOutputPath)%(Filename).xform.resx')">
@@ -54,4 +54,43 @@
     </ItemGroup>
   </Target>
 
+  <!--
+  Processes {Lambda} converters in WPF XAML files and generates code for them.
+  -->
+
+  <PropertyGroup>
+    <BuildTasksProjectDir>$(BuildRoot)\Tools\BuildTasks</BuildTasksProjectDir>
+    <BuildTasksAssembly>$(BuildOutputRoot)\ToolBinaries\BuildTasks\Microsoft.VisualStudioTools.BuildTasks.dll</BuildTasksAssembly>
+  </PropertyGroup>
+  <ItemGroup>
+    <BuildTasksSourceFiles Include="$(BuildTasksProjectDir)\*.csproj"/>
+    <BuildTasksSourceFiles Include="$(BuildTasksProjectDir)\**\*.cs"/>
+  </ItemGroup>
+
+  <!-- Use Exec rather than MSBuild here to completely isolate the task build - otherwise it interferes with the main build.
+       To avoid spawning a new msbuild.exe process again and again unnecessarily, do a quick up-to-date check (effectively
+       duplicating the one done by .csproj) on the target. -->
+  <Target Name="BuildBuildTasks" Inputs="@(BuildTasksSourceFiles)" Outputs="$(BuildTasksAssembly)">
+    <Exec Command='"$(MSBuildBinPath)\msbuild.exe" "$(BuildRoot)\Common\Tools\BuildTasks\BuildTasks.csproj"'/>
+  </Target>
+
+  <UsingTask AssemblyFile="$(BuildTasksAssembly)" TaskName="Microsoft.VisualStudioTools.BuildTasks.ExtractLambdasFromXaml"/>
+
+  <Target Name="ExtractLambdasFromXaml"
+          DependsOnTargets="BuildBuildTasks"
+          Inputs="@(Page)"
+          Outputs="@(Page->'$(IntermediateOutputPath)%(Filename).g.lambdas$(DefaultLanguageSourceExtension)')">
+    <ExtractLambdasFromXaml InputFileName="@(Page->'%(FullPath)')" OutputFileName="$(IntermediateOutputPath)%(Filename).g.lambdas$(DefaultLanguageSourceExtension)" Language="$(Language)">
+      <Output TaskParameter="OutputFileName" ItemName="Compile"/>
+      <Output TaskParameter="OutputFileName" ItemName="FileWrites"/>
+    </ExtractLambdasFromXaml>
+  </Target>
+
+  <PropertyGroup>
+    <CoreCompileDependsOn>
+      ExtractLambdasFromXaml;
+      $(CoreCompileDependsOn)
+    </CoreCompileDependsOn>
+  </PropertyGroup>
+
 </Project>