Run Chrome & FF serially to try and help flakiness

Author: kevinpschaaf

.travis.yml

@@ -17,7 +17,8 @@ before_script:
 #  '\n\033[31mERROR:\033[0m Typings are stale. Please run "npm run
 #  update-types".' && false)
 script:
-- node ./node_modules/.bin/polymer test --npm --module-resolution=node -l chrome -l firefox
+- node ./node_modules/.bin/polymer test --npm --module-resolution=node -l chrome
+- node ./node_modules/.bin/polymer test --npm --module-resolution=node -l firefox
 - if [ "${TRAVIS_PULL_REQUEST}" = "false" ]; then travis_wait 30 ./util/travis-sauce-test.sh; fi
 env:
   global: