Fix a bug that items can't be selected in list boxes

BUG=pdfium:328
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1538513002 .
diff --git a/xfa/src/fwl/src/basewidget/fwl_comboboximp.cpp b/xfa/src/fwl/src/basewidget/fwl_comboboximp.cpp
index 38f34d9..f1a80df 100644
--- a/xfa/src/fwl/src/basewidget/fwl_comboboximp.cpp
+++ b/xfa/src/fwl/src/basewidget/fwl_comboboximp.cpp
@@ -1157,7 +1157,7 @@
   prop.m_dwStates = FWL_WGTSTATE_Invisible;

   prop.m_pDataProvider = m_pProperties->m_pDataProvider;

   prop.m_pThemeProvider = m_pProperties->m_pThemeProvider;

-  m_pListBox.reset(IFWL_ListBox::Create(prop, m_pInterface));

+  m_pListBox.reset(IFWL_ListBox::CreateComboList(prop, m_pInterface));

   m_pListBox->Initialize();

 }

 void CFWL_ComboBoxImp::DisForm_InitComboEdit() {

@@ -1167,7 +1167,7 @@
   CFWL_WidgetImpProperties prop;

   prop.m_pParent = m_pInterface;

   prop.m_pThemeProvider = m_pProperties->m_pThemeProvider;

-  m_pEdit.reset(IFWL_Edit::Create(prop, m_pInterface));

+  m_pEdit.reset(IFWL_Edit::CreateComboEdit(prop, m_pInterface));

   m_pEdit->Initialize();

   static_cast<CFWL_ComboEditImp*>(m_pEdit->GetImpl())->SetOuter(m_pInterface);

 }