[LyX/master] Do not export the content of InsetMathBoxed as text in MathML

[Jean-Marc Lasgouttes]

commit 1186d90edf9a6702573f296d5642c5e61ceaaedf
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Tue Jul 23 23:44:58 2024 +0200

    Do not export the content of InsetMathBoxed as text in MathML
    
    \boxed{} is the only box in LaTeX that contains math. It is amusing
    that the example file that we had for ticket #13609 should not have
    been a problem since there is no reason to force <mtext> there.
---
 src/mathed/InsetMathBox.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/mathed/InsetMathBox.cpp b/src/mathed/InsetMathBox.cpp
index f06ffcf95d..62a11a15aa 100644
--- a/src/mathed/InsetMathBox.cpp
+++ b/src/mathed/InsetMathBox.cpp
@@ -402,7 +402,9 @@ void InsetMathBoxed::infoize(odocstream & os) const
 
 void InsetMathBoxed::mathmlize(MathMLStream & ms) const
 {
-	mathmlizeHelper(ms, cell(0), "class='boxed'");
+	ms << MTag("mrow", "class='boxed'");
+	ms << cell(0);
+	ms << ETag("mrow");
 }