[LyX/master] Revert "XHTML: remove DOCTYPE, as the document is then understood as HTML4/XHTML1, and not XHTML5."

Sat Sep 19 23:08:12 UTC 2020

commit da67bde61af6dfecef7a237b72b878fe30638a81
Author: Thibaut Cuvelier <tcuvelier at lyx.org>
Date:   Sun Sep 20 01:35:14 2020 +0200

    Revert "XHTML: remove DOCTYPE, as the document is then understood as HTML4/XHTML1, and not XHTML5."
    
    This reverts commit c8e2c17a: this makes some browsers unable to understand basic HTML entities.
---
 src/Buffer.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 0cf87de..2ef5768 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -2217,7 +2217,7 @@ Buffer::ExportStatus Buffer::writeLyXHTMLSource(odocstream & os,
 
 	if (output_preamble) {
 		os << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
-		   << "<!DOCTYPE html>\n"
+		   << "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN\" \"http://www.w3.org/Math/DTD/mathml2/xhtml-math11-f.dtd\">\n"
 		   // FIXME Language should be set properly.
 		   << "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n"
 		   << "<head>\n"
