Remove CLASSHASH defines in favour of an enum class.

xfa/fwl/theme/cfwl_formtp.cpp

Index: xfa/fwl/theme/cfwl_formtp.cpp
diff --git a/xfa/fwl/theme/cfwl_formtp.cpp b/xfa/fwl/theme/cfwl_formtp.cpp
index 6b876d2b403de414ae161869dc1fe3ba119123ac..75244373d490ccf629ae2cadee28a097f5170a12 100644
--- a/xfa/fwl/theme/cfwl_formtp.cpp
+++ b/xfa/fwl/theme/cfwl_formtp.cpp
@@ -60,12 +60,10 @@ FWL_Error CFWL_FormTP::Finalize() {
   return CFWL_WidgetTP::Finalize();
 }
 
-FX_BOOL CFWL_FormTP::IsValidWidget(IFWL_Widget* pWidget) {
-  if (!pWidget)
-    return FALSE;
-  uint32_t dwHash = pWidget->GetClassID();
-  return dwHash == FWL_CLASSHASH_Form;
+bool CFWL_FormTP::IsValidWidget(IFWL_Widget* pWidget) {
+  return pWidget && pWidget->GetClassID() == FWL_Type::Form;
 }
+
 uint32_t CFWL_FormTP::SetThemeID(IFWL_Widget* pWidget,
                                  uint32_t dwThemeID,
                                  FX_BOOL bChildren) {