Roll libxml to 2.9.3

third_party/libxml/src/HTMLtree.c

 /*
  * HTMLtree.c : implementation of access function for an HTML tree.
  *
  * See Copyright for the status of this software.
  *
  * daniel@veillard.com
  */
 
 
 #define IN_LIBXML
@@ skipping 650 matching lines @@
     }
     xmlOutputBufferWriteString(buf, "<!DOCTYPE ");
     xmlOutputBufferWriteString(buf, (const char *)cur->name);
     if (cur->ExternalID != NULL) {
         xmlOutputBufferWriteString(buf, " PUBLIC ");
         xmlBufWriteQuotedString(buf->buffer, cur->ExternalID);
         if (cur->SystemID != NULL) {
             xmlOutputBufferWriteString(buf, " ");
             xmlBufWriteQuotedString(buf->buffer, cur->SystemID);
         }
-    }  else if (cur->SystemID != NULL) {
+    } else if (cur->SystemID != NULL &&
+               xmlStrcmp(cur->SystemID, BAD_CAST "about:legacy-compat")) {
         xmlOutputBufferWriteString(buf, " SYSTEM ");
         xmlBufWriteQuotedString(buf->buffer, cur->SystemID);
     }
     xmlOutputBufferWriteString(buf, ">\n");
 }
 
 /**
  * htmlAttrDumpOutput:
  * @buf:  the HTML buffer output
  * @doc:  the document
@@ skipping 589 matching lines @@
 int
 htmlSaveFileEnc(const char *filename, xmlDocPtr cur, const char *encoding) {
     return(htmlSaveFileFormat(filename, cur, encoding, 1));
 }
 
 #endif /* LIBXML_OUTPUT_ENABLED */
 
 #define bottom_HTMLtree
 #include "elfgcchack.h"
 #endif /* LIBXML_HTML_ENABLED */