[FIX] base.xml: improve backwards compatibility of SearchView.filters template to resolve JS errors on OpenERP Apps where 2 different versions of the web client frameworm can be mixed

The incompatible change was introduced at revision
 rev. 3803 revid:xmo@openerp.com-20130304152047-8xaczg9qdx6ug2p1.

lp bug: https://launchpad.net/bugs/1158093 fixed

bzr revid: odo@openerp.com-20130321112020-l9fwle08s37z4oqi

addons/web/static/src/xml/base.xml

@@ -1520,7 +1520,7 @@
     <t t-esc="attrs.string"/>
 </button>
 <ul t-name="SearchView.filters">
-    <li t-foreach="widget.filters" t-as="filter" t-if="filter.visible()"
+    <li t-foreach="widget.filters" t-as="filter" t-if="!filter.visible || filter.visible()"
             t-att-title="filter.attrs.string ? filter.attrs.help : undefined">
         <t t-esc="filter.attrs.string or filter.attrs.help or filter.attrs.name or 'Ω'"/>
     </li>