[Tests] up to node v9.3, v8.9, v6.12

Author: ljharb

.travis.yml

@@ -2,9 +2,10 @@ language: node_js
 os:
  - linux
 node_js:
-  - "8.8"
+  - "9.3"
+  - "8.9"
   - "7.10"
-  - "6.11"
+  - "6.12"
   - "5.12"
   - "4.8"
   - "iojs-v3.3"
@@ -30,6 +31,14 @@ matrix:
   include:
     - node_js: "node"
       env: COVERAGE=true
+    - node_js: "9.2"
+      env: TEST=true ALLOW_FAILURE=true
+    - node_js: "9.1"
+      env: TEST=true ALLOW_FAILURE=true
+    - node_js: "9.0"
+      env: TEST=true ALLOW_FAILURE=true
+    - node_js: "8.8"
+      env: TEST=true ALLOW_FAILURE=true
     - node_js: "8.7"
       env: TEST=true ALLOW_FAILURE=true
     - node_js: "8.6"
@@ -66,6 +75,8 @@ matrix:
       env: TEST=true ALLOW_FAILURE=true
     - node_js: "7.0"
       env: TEST=true ALLOW_FAILURE=true
+    - node_js: "6.11"
+      env: TEST=true ALLOW_FAILURE=true
     - node_js: "6.10"
       env: TEST=true ALLOW_FAILURE=true
     - node_js: "6.9"