chore(travis): remove unused FF_TAR and CHROME_DEB

Author: chirayuk

scripts/travis/install.sh

@@ -5,8 +5,6 @@ set -e -o pipefail
 sh -e /etc/init.d/xvfb start
 
 DARTIUM_ZIP=http://storage.googleapis.com/dart-archive/channels/$CHANNEL/release/latest/dartium/dartium-linux-x64-release.zip
-FF_TAR=http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/$FIREFOX_VERSION/linux-x86_64/en-US/firefox-$FIREFOX_VERSION.tar.bz2
-CHROME_DEB=https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
 
 shopt -s nocasematch