Update nekohtml + xalan dependencies (#12871).

nekohtml 1.9.15 -> 1.9.19, now directly from Maven central
xerces 2.9.1 -> 2.11.0, now directly from Maven central

Change-Id: I7b9acd066f73ea546d46ce88065496c628ad5799

client-compiler/ivy.xml

@@ -65,6 +65,15 @@
         <dependency org="org.apache.httpcomponents" name="httpmime"
             rev="4.3.1" conf="build,ide -> default" />
 
+        <dependency org="net.sourceforge.nekohtml" name="nekohtml"
+            rev="1.9.19" conf="build,ide -> default" />
+        <dependency org="xalan" name="serializer" rev="2.7.1"
+            conf="build,ide -> default" />
+        <dependency org="xerces" name="xercesImpl" rev="2.11.0"
+            conf="build,ide -> default" />
+        <dependency org="xml-apis" name="xml-apis" rev="1.4.01"
+            conf="build,ide -> default" />
+
         <dependency org="com.vaadin" name="vaadin-client-compiler-deps"
             rev="1.0.2" conf="build,ide -> default" />