Fix build after Windows 1809 October Update merge

lib/Runtime/Base/CrossSite.cpp

@@ -128,10 +128,10 @@ namespace Js
         for (uint16 i = 0; i < length; i++)
         {
             Var value = display->GetItem(i);
-            if (UnscopablesWrapperObject::Is(value))
+            if (Js::VarIs<UnscopablesWrapperObject>(value))
             {
                 // Here we are marshalling the wrappedObject and then ReWrapping th object in the new context.
-                RecyclableObject* wrappedObject = UnscopablesWrapperObject::FromVar(value)->GetWrappedObject();
+                RecyclableObject* wrappedObject = Js::VarTo<UnscopablesWrapperObject>(value)->GetWrappedObject();
                 ScriptContext* wrappedObjectScriptContext = wrappedObject->GetScriptContext();
                 value = JavascriptOperators::ToUnscopablesWrapperObject(CrossSite::MarshalVar(scriptContext,
                   wrappedObject, wrappedObjectScriptContext), scriptContext);

lib/Runtime/Library/JavascriptError.cpp

@@ -773,8 +773,8 @@ namespace Js
             // two error codes is morally equivalent in typeof scenario. Special case this here
             // because we do not want typeof to leak these exceptions.
             && !(errorObject != nullptr
-                && Js::JavascriptError::Is(errorObject)
-                && Js::JavascriptError::FromVar(errorObject)->GetErrorType() == kjstWinRTError
+                && Js::VarIs<Js::JavascriptError>(errorObject)
+                && Js::VarTo<Js::JavascriptError>(errorObject)->GetErrorType() == kjstWinRTError
                 && hr == TYPE_E_ELEMENTNOTFOUND)
 #endif
             ;

lib/Runtime/Types/UnscopablesWrapperObject.cpp

@@ -6,23 +6,6 @@
 
 namespace Js
 {
-    bool UnscopablesWrapperObject::Is(Var aValue)
-    {
-        return JavascriptOperators::GetTypeId(aValue) == TypeIds_UnscopablesWrapperObject;
-    }
-
-    UnscopablesWrapperObject* UnscopablesWrapperObject::FromVar(Var aValue)
-    {
-        AssertOrFailFast(UnscopablesWrapperObject::Is(aValue));
-        return static_cast<UnscopablesWrapperObject*>(aValue);
-    }
-
-    UnscopablesWrapperObject* UnscopablesWrapperObject::UnsafeFromVar(Var aValue)
-    {
-        Assert(UnscopablesWrapperObject::Is(aValue));
-        return static_cast<UnscopablesWrapperObject*>(aValue);
-    }
-
     PropertyQueryFlags UnscopablesWrapperObject::HasPropertyQuery(PropertyId propertyId, _Inout_opt_ PropertyValueInfo* info)
     {
         return JavascriptConversion::BooleanToPropertyQueryFlags(JavascriptOperators::HasPropertyUnscopables(wrappedObject, propertyId));

lib/Runtime/Types/UnscopablesWrapperObject.h

@@ -25,9 +25,6 @@ namespace Js
 
         public:
             UnscopablesWrapperObject(RecyclableObject *wrappedObject, StaticType * type) : RecyclableObject(type), wrappedObject(wrappedObject) {}
-            static bool Is(Var aValue);
-            static UnscopablesWrapperObject* FromVar(Var value);
-            static UnscopablesWrapperObject* UnsafeFromVar(Var value);
             RecyclableObject *GetWrappedObject() { return wrappedObject; }
             virtual PropertyQueryFlags HasPropertyQuery(PropertyId propertyId, _Inout_opt_ PropertyValueInfo* info) override;
             virtual BOOL HasOwnProperty(PropertyId propertyId) override;