Revert "Remove support for MSVC"

sky/engine/bindings/core/v8/ScriptWrappable.h

Index: sky/engine/bindings/core/v8/ScriptWrappable.h
diff --git a/sky/engine/bindings/core/v8/ScriptWrappable.h b/sky/engine/bindings/core/v8/ScriptWrappable.h
index 3f5f3a8a68f777fa7c69fba035df91b9da64fc49..77445f92147ad210eacc3b451f54e874f9b96283 100644
--- a/sky/engine/bindings/core/v8/ScriptWrappable.h
+++ b/sky/engine/bindings/core/v8/ScriptWrappable.h
@@ -48,6 +48,26 @@ namespace blink {
  * variable which increase the size of instances. Some of the classes sensitive
  * to the size inherit from this class. So this class must be zero size.
  */
+#if COMPILER(MSVC)
+// VC++ 2013 doesn't support EBCO (Empty Base Class Optimization). It causes
+// that not always pointers to an empty base class are aligned to 4 byte
+// alignment. For example,
+//
+//   class EmptyBase1 {};
+//   class EmptyBase2 {};
+//   class Derived : public EmptyBase1, public EmptyBase2 {};
+//   Derived d;
+//   // &d                           == 0x1000
+//   // static_cast<EmptyBase1*>(&d) == 0x1000
+//   // static_cast<EmptyBase2*>(&d) == 0x1001  // Not 4 byte alignment!
+//
+// This doesn't happen with other compilers which support EBCO. All the
+// addresses in the above example will be 0x1000 with EBCO supported.
+//
+// Since v8::Object::SetAlignedPointerInInternalField requires the pointers to
+// be aligned, we need a hack to specify at least 4 byte alignment to MSVC.
+__declspec(align(4))
+#endif
 class ScriptWrappableBase {
 public:
     template<typename T>