Update dependencies from https://github.com/dotnet/winforms build 20190410.2 (#560)

- Microsoft.Private.Winforms - 4.8.0-preview4.19210.2

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -50,9 +50,9 @@
       <Sha>e0a01a12c2676d69cefa61aa2526a414d7f2dabb</Sha>
       <SourceBuildId>5589</SourceBuildId>
     </Dependency>
-    <Dependency Name="Microsoft.Private.Winforms" Version="4.8.0-preview4.19209.7">
+    <Dependency Name="Microsoft.Private.Winforms" Version="4.8.0-preview4.19210.2">
       <Uri>https://github.com/dotnet/winforms</Uri>
-      <Sha>ccf39ec74d9e673f2a994be2a9d67418c78c8c82</Sha>
+      <Sha>9f7f6a960c673d48d31bafc90603b2e313f95ca2</Sha>
       <SourceBuildId>6173</SourceBuildId>
     </Dependency>
     <Dependency Name="System.Drawing.Common" Version="4.6.0-preview4.19208.6" CoherentParentDependency="Microsoft.NETCore.App">

eng/Versions.props

@@ -5,7 +5,7 @@
     <PreReleaseVersionLabel>preview4</PreReleaseVersionLabel>
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <SystemReflectionMetadataLoadContextVersion>4.6.0-preview4.19208.6</SystemReflectionMetadataLoadContextVersion>
-    <MicrosoftPrivateWinformsVersion>4.8.0-preview4.19209.7</MicrosoftPrivateWinformsVersion>
+    <MicrosoftPrivateWinformsVersion>4.8.0-preview4.19210.2</MicrosoftPrivateWinformsVersion>
     <SystemDrawingCommonVersion>4.6.0-preview4.19208.6</SystemDrawingCommonVersion>
     <SystemDirectoryServicesVersion>4.6.0-preview4.19208.6</SystemDirectoryServicesVersion>
   </PropertyGroup>