Dont use zero width sapce for EZP-29882

src/lib/eZ/RichText/Resources/stylesheets/docbook/xhtml5/edit/core.xsl

@@ -585,7 +585,7 @@
       <xsl:call-template name="ezattribute"/>
       <xsl:apply-templates/>
       <xsl:if test="./docbook:ezattribute or not(node())">
-        <xsl:text> </xsl:text>
+        <xsl:text>ao-upcast-placeholder</xsl:text>
       </xsl:if>
     </xsl:element>
   </xsl:template>

tests/lib/eZ/RichText/Converter/Xslt/_fixtures/xhtml5/edit/023-embedInline.xml

@@ -1,10 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <section xmlns="http://ez.no/namespaces/ezpublish5/xhtml5/edit">
-  <p>Some <span data-ezelement="ezembedinline" id="id3" data-href="ezcontent://601" data-ezview="embed-inline-custom" class="embedClass" data-ezalign="left"> </span> for the otherwise unremarkable paragraph.</p>
+  <p>Some <span data-ezelement="ezembedinline" id="id3" data-href="ezcontent://601" data-ezview="embed-inline-custom" class="embedClass" data-ezalign="left">ao-upcast-placeholder</span> for the otherwise unremarkable paragraph.</p>
   <p>This paragraph is just showing off its <span data-ezelement="ezembedinline" id="id5" data-href="ezcontent://501" data-ezview="embed-inline" class="embedClass2" data-ezalign="right">
     <span data-ezelement="ezconfig">
       <span data-ezelement="ezvalue" data-ezvalue-key="size">medium</span>
     </span>
   </span> content.</p>
-  <p>Some<span data-ezattribute-name-1="value 1" data-ezattribute-name-2="value 2" data-ezelement="ezembedinline" id="id4" data-href="ezcontent://601"> </span> content.</p>
+  <p>Some<span data-ezattribute-name-1="value 1" data-ezattribute-name-2="value 2" data-ezelement="ezembedinline" id="id4" data-href="ezcontent://601">ao-upcast-placeholder</span> content.</p>
 </section>

tests/lib/eZ/RichText/Converter/Xslt/_fixtures/xhtml5/edit/035-itemizedListWithNestedElements.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <section xmlns="http://ez.no/namespaces/ezpublish5/xhtml5/edit">
   <ul>
-    <li>This is a list item <span data-ezelement="ezembedinline" data-href="ezcontent://52" data-ezview="embed-inline"> </span></li>
+    <li>This is a list item <span data-ezelement="ezembedinline" data-href="ezcontent://52" data-ezview="embed-inline">ao-upcast-placeholder</span></li>
   </ul>
 </section>