ooxml: import combobox sdt control

This patch modifies the importer to reuse the code that imports the
dropdown control and creates a combo box with it.

The only drawback is that the combobox tag is transformed into a
dropdownlist when exported back, but it doesn't seem to be an issue
from the point of view of the user.

Change-Id: I340d0cf02d8c5ea575ad4784a1242d2a3e9bd214

writerfilter/source/dmapper/DomainMapper.cxx

@@ -2203,6 +2203,7 @@ void DomainMapper::sprmWithProps( Sprm& rSprm, PropertyMapPtr rContext )
     }
     break;
     case NS_ooxml::LN_CT_SdtPr_dropDownList:
+    case NS_ooxml::LN_CT_SdtPr_comboBox:
     {
         writerfilter::Reference<Properties>::Pointer_t pProperties = rSprm.getProps();
         if (pProperties.get() != NULL)

writerfilter/source/ooxml/model.xml

@@ -18774,19 +18774,6 @@
           </attribute>
         </optional>
       </define>
-      <define name="CT_SdtComboBox">
-        <zeroOrMore>
-          <element name="listItem">
-            <ref name="CT_SdtListItem"/>
-          </element>
-        </zeroOrMore>
-        <optional>
-          <attribute name="lastValue">
-            <text/>
-            <xs:documentation>Combo Box Last Saved Value</xs:documentation>
-          </attribute>
-        </optional>
-      </define>
       <define name="CT_SdtDocPart">
         <optional>
           <element name="docPartGallery">
@@ -18896,7 +18883,7 @@
                   <ref name="CT_OnOff"/>
                 </element>
                 <element name="comboBox">
-                  <ref name="CT_SdtComboBox"/>
+                  <ref name="CT_SdtDropDownList"/>
                 </element>
                 <element name="w14:checkbox">
                   <ref name="CT_SdtCheckbox"/>