Update Travis distro to precise, except for legacy PHP

Author: clue

.travis.yml

@@ -1,27 +1,27 @@
 language: php
 
 php:
-  - 5.3
+# - 5.3 # requires old distro, see below
   - 5.4
   - 5.5
   - 5.6
   - 7
+  - hhvm # ignore errors, see below
 
 # lock distro so new future defaults will not break the build
-dist: precise
+dist: trusty
 
-# also test against HHVM, but require "trusty" and ignore errors
 # also test lowest dependencies on PHP 5.3 and PHP 7
 matrix:
   include:
     - php: 5.3
+      dist: precise
       env:
+        -
         - DEPENDENCIES=lowest
     - php: 7.0
       env:
         - DEPENDENCIES=lowest
-    - php: hhvm
-      dist: trusty
   allow_failures:
     - php: hhvm