MathML test case: fix a typo.

It was bugging me when looking at XHTML output: I was wondering if LyX was doing anything weird about ligatures! Hopefully not.

autotests/mathmacros/testcases_basic.lyx

@@ -1,15 +1,15 @@
 #LyX 2.4 created this file. For more info see https://www.lyx.org/
-\lyxformat 572
+\lyxformat 614
 \begin_document
 \begin_header
 \save_transient_properties true
 \origin unavailable
 \textclass article
 \use_default_options false
-\maintain_unincluded_children false
+\maintain_unincluded_children no
 \language english
 \language_package default
-\inputencoding auto
+\inputencoding auto-legacy
 \fontencoding auto
 \font_roman "default" "default"
 \font_sans "default" "default"
@@ -18,7 +18,9 @@
 \font_default_family default
 \use_non_tex_fonts false
 \font_sc false
-\font_osf false
+\font_roman_osf false
+\font_sans_osf false
+\font_typewriter_osf false
 \font_sf_scale 100 100
 \font_tt_scale 100 100
 \use_microtype false
@@ -52,6 +54,7 @@
 \justification true
 \use_refstyle 0
 \use_minted 0
+\use_lineno 0
 \index Index
 \shortcut idx
 \color #008000
@@ -70,9 +73,13 @@
 \tablestyle default
 \tracking_changes false
 \output_changes false
+\change_bars false
+\postpone_fragile_content false
 \html_math_output 0
 \html_css_as_file 0
 \html_be_strict false
+\docbook_table_output 0
+\docbook_mathml_prefix 1
 \end_header
 
 \begin_body
@@ -82,7 +89,8 @@ Macro Testcases
 \end_layout
 
 \begin_layout Enumerate
-Simple macro definitions with position awareness: 
+Simple macro definitions with position awareness:
+ 
 \begin_inset FormulaMacro
 \newcommand{\bla}{42}
 \end_inset
@@ -95,12 +103,13 @@ Simple macro definitions with position awareness:
 
 \end_inset
 
-now redined as 
+now redefined as 
 \begin_inset FormulaMacro
 \renewcommand{\bla}{21}
 \end_inset
 
-, such that
+,
+ such that
 \begin_inset Formula 
 \[
 \bla\mbox{ should look like }21.
@@ -112,7 +121,8 @@ now redined as
 \end_layout
 
 \begin_layout Enumerate
-Redefinitions of macros appearing in the definition of another macro: 
+Redefinitions of macros appearing in the definition of another macro:
+ 
 \begin_inset FormulaMacro
 \newcommand{\fooa}{x}
 \end_inset
@@ -176,7 +186,8 @@ gives the following:
 \end_layout
 
 \begin_layout Enumerate
-Arity change: 
+Arity change:
+ 
 \begin_inset FormulaMacro
 \newcommand{\foo}{-}
 \end_inset
@@ -198,7 +209,8 @@ Arity change:
 \end_layout
 
 \begin_layout Enumerate
-Arity change with incomplete arguments at line end: 
+Arity change with incomplete arguments at line end:
+ 
 \begin_inset FormulaMacro
 \renewcommand{\foo}{-}
 \end_inset
@@ -220,7 +232,8 @@ Arity change with incomplete arguments at line end:
 \end_layout
 
 \begin_layout Enumerate
-Recursion: 
+Recursion:
+ 
 \begin_inset FormulaMacro
 \renewcommand{\foo}[1]{\foo{#1}{}}
 \end_inset
@@ -231,7 +244,8 @@ Recursion:
 \end_layout
 
 \begin_layout Enumerate
-Recursive usage: 
+Recursive usage:
+ 
 \begin_inset FormulaMacro
 \renewcommand{\foo}[3]{\frac{{\displaystyle #1}\,{\displaystyle #2}}{{\displaystyle #3}}}
 \end_inset
@@ -254,8 +268,8 @@ Folding/Unfolding:
 \end_inset
 
 .
- Start using Ctrl-+ and Ctrl– when you are inside of the macro to fold and
- unfold, e.g.
+ Start using Ctrl-+ and Ctrl– when you are inside of the macro to fold and unfold,
+ e.g.
  here:
 \begin_inset Formula 
 \[
@@ -268,7 +282,8 @@ Folding/Unfolding:
 \end_layout
 
 \begin_layout Enumerate
-Scripts: 
+Scripts:
+ 
 \begin_inset FormulaMacro
 \renewcommand{\foo}[3][A][B]{(#1,#2)#3}
 \end_inset