Breaking: drop support for Node < 6 (#223)

* Chore: add supported Node.js versions to CI

Wanted to add Node v11 to the list of versions in CI and noticed a few others were missing. Do we want to drop support for Node@<6 at some point?

* Update engines field in package.json

Author: kaicataldo

.travis.yml

@@ -1,9 +1,10 @@
 language: node_js
 node_js:
-    - "0.10"
-    - "0.12"
-    - iojs
-    - "4"
+    - "6"
+    - "8"
+    - "9"
+    - "10"
+    - "11"
 sudo: false
 script: "npm test"
 after_success:

lib/doctrine.js

@@ -28,7 +28,6 @@
             return func.call(obj, name);
         };
     }());
-
     function shallowCopy(obj) {
         var ret = {}, key;
         for (key in obj) {

package.json

@@ -5,7 +5,7 @@
   "main": "lib/doctrine.js",
   "version": "2.1.0",
   "engines": {
-    "node": ">=0.10.0"
+    "node": ">=6.0.0"
   },
   "directories": {
     "lib": "./lib"