Travis: don't need alex, happy.

.travis.yml

@@ -12,16 +12,11 @@ env:
 before_install:
  - travis_retry sudo add-apt-repository -y ppa:hvr/ghc
  - travis_retry sudo apt-get update
- - travis_retry sudo apt-get install cabal-install-1.18 ghc-$GHCVER alex happy
+ - travis_retry sudo apt-get install cabal-install-1.18 ghc-$GHCVER
  - export PATH=/opt/ghc/$GHCVER/bin:$PATH
 
 install:
  - cabal-1.18 update
- - |
-   if [ $GHCVER = "head" ] || [ $GHCVER = "7.8.2" ]; then
-     cabal-1.18 install happy alex
-     export PATH=$HOME/.cabal/bin:$PATH
-   fi
 # - git clone https://github.com/jgm/pandoc-types && cd pandoc-types && cabal-1.18 install && cd ..
  - cabal-1.18 install --only-dependencies --enable-tests