Revert "Remove support for MSVC"

sky/engine/platform/PlatformExport.h

Index: sky/engine/platform/PlatformExport.h
diff --git a/sky/engine/platform/PlatformExport.h b/sky/engine/platform/PlatformExport.h
index e8f6e572e19b6aa82e77fc16abdd7f7da698b60f..8230fbb80fe30d491e97ecfdbeea00502c290466 100644
--- a/sky/engine/platform/PlatformExport.h
+++ b/sky/engine/platform/PlatformExport.h
@@ -37,9 +37,30 @@
 #endif
 
 #if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+#if BLINK_PLATFORM_IMPLEMENTATION
+#define PLATFORM_EXPORT __declspec(dllexport)
+#else
+#define PLATFORM_EXPORT __declspec(dllimport)
+#endif
+#else // defined(WIN32)
 #define PLATFORM_EXPORT __attribute__((visibility("default")))
+#endif
 #else // defined(COMPONENT_BUILD)
 #define PLATFORM_EXPORT
 #endif
 
+#if defined(_MSC_VER)
+// MSVC Compiler warning C4275:
+// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
+// Note that this is intended to be used only when no access to the base class'
+// static data is done through derived classes or inline methods. For more info,
+// see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
+//
+// This pragma will allow exporting a class that inherits from a non-exported
+// base class, anywhere in the Blink platform component. This is only
+// a problem when using the MSVC compiler on Windows.
+#pragma warning(suppress:4275)
+#endif
+
 #endif // PlatformExport_h