xmlTextConcat works with comments and PI nodes (bug #355962). fix

* tree.c: xmlTextConcat works with comments and PI nodes (bug #355962).
* parser.c: fix resulting tree corruption when using XML namespace
  with existing doc in xmlParseBalancedChunkMemoryRecover.
diff --git a/parser.c b/parser.c
index ceb91d2..e30427c 100644
--- a/parser.c
+++ b/parser.c
@@ -11903,6 +11903,9 @@
     } else {
 	ctxt->myDoc = newDoc;
 	newDoc->children->doc = doc;
+	/* Ensure that doc has XML spec namespace */
+	xmlSearchNsByHref(doc, (xmlNodePtr)doc, XML_XML_NAMESPACE);
+	newDoc->oldNs = doc->oldNs;
     }
     ctxt->instate = XML_PARSER_CONTENT;
     ctxt->depth = depth;
@@ -11963,6 +11966,7 @@
     xmlFreeParserCtxt(ctxt);
     newDoc->intSubset = NULL;
     newDoc->extSubset = NULL;
+    newDoc->oldNs = NULL;
     xmlFreeDoc(newDoc);
     
     return(ret);