Fix failing CI tests (#460)

* bump node version to 6
* use default travis osx_image of xcode9.4
* comment out flakey local test

.travis.yml

@@ -7,77 +7,60 @@ addons:
 env:
   global:
     - SAUCE_USERNAME=snay
-  - TRAVIS_NODE_VERSION="4.2"
+    - TRAVIS_NODE_VERSION=6
+    - ANDROID_API_LEVEL=28
+    - ANDROID_BUILD_TOOLS_VERSION=28.0.3
+
+language: node_js
+node_js: 6  
+
+# anchor/alias: https://medium.com/@tommyvn/travis-yml-dry-with-anchors-8b6a3ac1b027
+_android: &_android
+  language: android
+  os: linux
+  jdk: oraclejdk8
+  android:
+    components:
+      - tools
+      - build-tools-$ANDROID_BUILD_TOOLS_VERSION
+      - android-$ANDROID_API_LEVEL
+    licenses:
+      - 'android-sdk-preview-license-.+'
+      - 'android-sdk-license-.+'
+      - 'google-gdk-license-.+'
 
 matrix:
   include:
+    # # one local test, without saucelabs
+    # - env: PLATFORM=local
+    #   os: osx
+    #   osx_image: xcode9
+
+    # many tests with saucelabs
+
     - env: PLATFORM=browser-chrome
-    os: linux
-    language: node_js
-    node_js: '4.2'
     - env: PLATFORM=browser-firefox
-    os: linux
-    language: node_js
-    node_js: '4.2'
     - env: PLATFORM=browser-safari
-    os: linux
-    language: node_js
-    node_js: '4.2'
     - env: PLATFORM=browser-edge
-    os: linux
+
-    language: node_js
-    node_js: '4.2'
-# iOS 9 not supported by iOS WKWebView implementation
-#  - env: PLATFORM=ios-9.3
-#    os: osx
-#    osx_image: xcode8.3
-#    language: node_js
-#    node_js: '4.2'
     - env: PLATFORM=ios-10.0
       os: osx
-    osx_image: xcode8.3
+      osx_image: xcode9
-    language: node_js
+      
-    node_js: '4.2'
     - env: PLATFORM=android-4.4
-    os: linux
+      <<: *_android
-    language: android
-    jdk: oraclejdk8
-    android:
-      components:
-      - tools
-      - platform-tools
-      - tools
-      - build-tools-26.0.2
     - env: PLATFORM=android-5.1
-    os: linux
+      <<: *_android
-    language: android
-    jdk: oraclejdk8
-    android:
-      components:
-      - tools
-      - platform-tools
-      - tools
-      - build-tools-26.0.2
     - env: PLATFORM=android-6.0
-    os: linux
+      <<: *_android
-    language: android
-    jdk: oraclejdk8
-    android:
-      components:
-      - tools
-      - platform-tools
-      - tools
-      - build-tools-26.0.2
     - env: PLATFORM=android-7.0
-    os: linux
+      <<: *_android
-    language: android
+    - env: PLATFORM=android-7.1
-    jdk: oraclejdk8
+      <<: *_android
-    android:
+    - env: PLATFORM=android-8.0
-      components:
+      <<: *_android
-      - tools
+    - env: PLATFORM=android-8.1
-      - platform-tools
+      <<: *_android
-      - tools
-      - build-tools-26.0.2
 
 before_install:
 - rm -rf ~/.nvm && git clone https://github.com/creationix/nvm.git ~/.nvm && (cd ~/.nvm