We don't need these chrome apt dependencies on Travis

As we're using Firefox there which comes built-in.
Also, when we change that, it will be fore the Remote driver towards
SauceLabs, and not chrome.

.travis.yml

@@ -7,8 +7,6 @@ addons:
     - ubuntu-toolchain-r-test
     packages:
     - g++-4.8
-    - libnss3-dev
-    - libgconf-2-4
 cache:
   apt: true
   directories: