Re-enabled OS X builds.

This reverts commit dcad9e208150d56c350eb3098a67aaae9f02d10e.
The issue was caused by:
https://github.com/HaxeFoundation/neko/commit/4ffdbe71ee1b98daf2d27b933fe310f673295514
Fixed in:
https://github.com/HaxeFoundation/neko/commit/468b70e43dd973ae8a5497c4599c93de8eb5033b

.travis.yml

@@ -82,30 +82,30 @@ matrix:
     #######
     # osx #
     #######
-    #- os: osx
-    #  env: TEST=third-party
-    #- os: osx
-    #  env: TEST=macro
-    #- os: osx
-    #  env:
-    #    - TEST=neko
-    #    - BINTRAY=1
-    #- os: osx
-    #  env: TEST=js
-    #- os: osx
-    #  env: TEST=php
-    #- os: osx
-    #  env: TEST=cpp
-    #- os: osx
-    #  env: TEST=flash9
-    #- os: osx
-    #  env: TEST=as3
-    #- os: osx
-    #  env: TEST=java
-    #- os: osx
-    #  env: TEST=cs
-    #- os: osx
-    #  env: TEST=python
+    - os: osx
+      env: TEST=third-party
+    - os: osx
+      env: TEST=macro
+    - os: osx
+      env:
+        - TEST=neko
+        - BINTRAY=1
+    - os: osx
+      env: TEST=js
+    - os: osx
+      env: TEST=php
+    - os: osx
+      env: TEST=cpp
+    - os: osx
+      env: TEST=flash9
+    - os: osx
+      env: TEST=as3
+    - os: osx
+      env: TEST=java
+    - os: osx
+      env: TEST=cs
+    - os: osx
+      env: TEST=python
 
 install:
   # Install haxe and neko dependencies