travis: Add yarn and nodejs caching (#2504)

Also cache node_module and yarn cache in Travis test process.
Improves speed for Travis tests.

diff --git a/.travis.yml b/.travis.yml
index 91454c9a203ee2fd0ca9a7eb23059d20a80cc847..90a33f51d712ee0fd724fc057984e9bd34d13b8f 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,9 @@
 language: ruby
-cache: bundler
+cache:
+  bundler: true
+  yarn: true
+  directories:
+    - node_modules
 dist: trusty
 sudo: false