build: caching all dependencies

.travis.yml

@@ -1,20 +1,27 @@
+os: linux
 language: node_js
 node_js:
   - 'node'
-sudo: required
 dist: trusty
 addons:
   chrome: stable
 before_script:
   - 'sudo chown root /opt/google/chrome/chrome-sandbox'
   - 'sudo chmod 4755 /opt/google/chrome/chrome-sandbox'
-before_install:
-  - npm cache clean --force
 script: npm run test:angular-versions
-matrix:
-  notifications:
-    email:
-      recipients:
-        - ike18t@gmail.com
-      on_success: change
-      on_failure: change
+cache:
+  directories:
+    - $HOME/.node-gyp/
+    - $HOME/.npm/
+    - node_modules/
+    - e2e/angular5/node_modules/
+    - e2e/angular5-jest/node_modules/
+    - e2e/angular6/node_modules/
+    - e2e/angular6-jest/node_modules/
+    - e2e/angular7/node_modules/
+    - e2e/angular7-jest/node_modules/
+    - e2e/angular8/node_modules/
+    - e2e/angular8-jest/node_modules/
+    - e2e/angular9-ivy-false/node_modules/
+    - e2e/angular9-ivy-true/node_modules/
+    - e2e/angular9-jest/node_modules/