Always install xfonts-mathml package if it is available.

build/install-build-deps.sh

 #!/bin/bash -e
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to install everything needed to build chromium (well, ideally, anyway)
 # See https://chromium.googlesource.com/chromium/src/+/master/docs/linux_build_instructions.md
 
 usage() {
@@ skipping 225 matching lines @@
 if package_exists libbrlapi0.6; then
   dev_list="${dev_list} libbrlapi0.6"
 else
   dev_list="${dev_list} libbrlapi0.5"
 fi
 if package_exists apache2-bin; then
   dev_list="${dev_list} apache2-bin"
 else
   dev_list="${dev_list} apache2.2-bin"
 fi
-if package_exists fonts-stix; then
-  dev_list="${dev_list} fonts-stix"
-else
+if package_exists xfonts-mathml; then
   dev_list="${dev_list} xfonts-mathml"
 fi
 if package_exists fonts-indic; then
-    dev_list="${dev_list} fonts-indic"
+  dev_list="${dev_list} fonts-indic"
 else
-    dev_list="${dev_list} ttf-indic-fonts"
+  dev_list="${dev_list} ttf-indic-fonts"
 fi
 if package_exists php7.0-cgi; then
-    dev_list="${dev_list} php7.0-cgi libapache2-mod-php7.0"
+  dev_list="${dev_list} php7.0-cgi libapache2-mod-php7.0"
 else
-    dev_list="${dev_list} php5-cgi libapache2-mod-php5"
+  dev_list="${dev_list} php5-cgi libapache2-mod-php5"
 fi
 # Ubuntu 16.04 has this package deleted.
 if package_exists ttf-kochi-gothic; then
-    dev_list="${dev_list} ttf-kochi-gothic"
+  dev_list="${dev_list} ttf-kochi-gothic"
 fi
 # Ubuntu 16.04 has this package deleted.
 if package_exists ttf-kochi-mincho; then
-    dev_list="${dev_list} ttf-kochi-mincho"
+  dev_list="${dev_list} ttf-kochi-mincho"
 fi
 
 # Some packages are only needed if the distribution actually supports
 # installing them.
 if package_exists appmenu-gtk; then
   lib_list="$lib_list appmenu-gtk"
 fi
 
 # When cross building for arm/Android on 64-bit systems the host binaries
 # that are part of v8 need to be compiled with -m32 which means
@@ skipping 221 matching lines @@
   # only contains libcrypto.so.1.0.0 and not the symlink needed for
   # linking (libcrypto.so).
   create_library_symlink /lib/i386-linux-gnu/libcrypto.so.1.0.0 \
       /usr/lib/i386-linux-gnu/libcrypto.so
 
   create_library_symlink /lib/i386-linux-gnu/libssl.so.1.0.0 \
       /usr/lib/i386-linux-gnu/libssl.so
 else
   echo "Skipping symbolic links for NaCl."
 fi