Bug 1668706 - Fix invalid handle handling of FileDescriptor::Clone() on Windows r=jld

It needs to check for both nullptr and INVALID_HANDLE_VALUE

Differential Revision: https://phabricator.services.mozilla.com/D92186

ipc/glue/FileDescriptor.cpp

@@ -105,7 +105,7 @@ FileDescriptor::UniquePlatformHandle FileDescriptor::Clone(
   FileDescriptor::PlatformHandleType newHandle;
 
 #ifdef XP_WIN
-  if (aHandle == INVALID_HANDLE_VALUE) {
+  if (aHandle == INVALID_HANDLE_VALUE || aHandle == nullptr) {
     return UniqueFileHandle();
   }
   if (::DuplicateHandle(GetCurrentProcess(), aHandle, GetCurrentProcess(),