Test on multiple Node versions.

.travis.yml

@@ -1,11 +1,15 @@
 language: node_js
 node_js:
+  - 10
   - node
+env:
+  - DEFAULT_NODE_VERSION=10
 script:
   - npm test
 after_success:
-  - npm run coverage:report
-  - ./.travis_publish
-cache:
-  directories:
-    - node_modules
+  - if [ "$TRAVIS_NODE_VERSION" == "$DEFAULT_NODE_VERSION" ]; then
+      npm install coveralls;
+      node_modules/.bin/jest --coverage --coverageReporters=text-lcov |
+        node_modules/.bin/coveralls;
+      ./.travis_publish;
+    fi

package.json

@@ -39,7 +39,6 @@
     "test": "npm run jest",
     "test:dev": "npm run jest -- --watch",
     "test:debug": "node --debug-brk ./node_modules/.bin/jest --runInBand src",
-    "coverage:report": "cat ./coverage/lcov.info | coveralls",
     "build": "npm run build:lib && npm run build:module && npm run build:window && npm run build:browser && npm run build:popup:template",
     "build:lib": "rm -rf lib && babel src --env-name production -d lib",
     "build:module": "rm -rf module && babel src --env-name module -d module",
@@ -73,7 +72,6 @@
     "babel-jest": "^23.6.0",
     "babel-loader": "^8.0.2",
     "clean-webpack-plugin": "^0.1.19",
-    "coveralls": "^3.0.2",
     "cross-env": "^5.0.5",
     "css-loader": "^1.0.0",
     "eslint": "^5.6.0",