Add **Web platform with Emscripten**

Source/Engine/Main/Main.Build.cs

@@ -74,6 +74,9 @@ public class Main : EngineModule
         case TargetPlatform.iOS:
             options.SourcePaths.Add(Path.Combine(FolderPath, "Default"));
             break;
+        case TargetPlatform.Web:
+            options.SourcePaths.Add(Path.Combine(FolderPath, "Web"));
+            break;
         default: throw new InvalidPlatformException(options.Platform.Target);
         }
     }

Source/Engine/Main/Web/main.cpp

@@ -0,0 +1,12 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#if PLATFORM_WEB
+
+#include "Engine/Engine/Engine.h"
+
+int main()
+{
+    return Engine::Main(TEXT(""));
+}
+
+#endif