shrink assign style dialog to min

Change-Id: I204b239c4898ab6a7b25a7e935eb0d81e470f08c
Reviewed-on: https://gerrit.libreoffice.org/65430
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/uiconfig/swriter/ui/assignstylesdialog.ui

@@ -47,6 +47,8 @@
     <property name="border_width">6</property>
     <property name="title" translatable="yes" context="assignstylesdialog|AssignStylesDialog">Assign Styles</property>
     <property name="modal">True</property>
+    <property name="default_width">0</property>
+    <property name="default_height">0</property>
     <property name="type_hint">dialog</property>
     <child>
       <placeholder/>