Destroy window before cleaning up combobox

fpdfsdk/formfiller/cffl_formfiller.cpp

Index: fpdfsdk/formfiller/cffl_formfiller.cpp
diff --git a/fpdfsdk/formfiller/cffl_formfiller.cpp b/fpdfsdk/formfiller/cffl_formfiller.cpp
index f2c34647d077b9fa6caa5bdcb064f9ad57df20d2..92e9282a74923321250a8cdf2b7da406e45b5d1d 100644
--- a/fpdfsdk/formfiller/cffl_formfiller.cpp
+++ b/fpdfsdk/formfiller/cffl_formfiller.cpp
@@ -27,6 +27,10 @@ CFFL_FormFiller::CFFL_FormFiller(CPDFDoc_Environment* pApp,
 }
 
 CFFL_FormFiller::~CFFL_FormFiller() {
+  DestroyWindows();
+}
+
+void CFFL_FormFiller::DestroyWindows() {
   for (const auto& it : m_Maps) {
     CPWL_Wnd* pWnd = it.second;
     CFFL_PrivateData* pData = (CFFL_PrivateData*)pWnd->GetAttachedData();