Fix the version of npm package (improve reproducibility)

Change-Id: Ib921474be0ac287efbe57c8157b31107f7120f17
diff --git a/gce/jenkins-slave.sh b/gce/jenkins-slave.sh
index 88311db..ddb5a78 100644
--- a/gce/jenkins-slave.sh
+++ b/gce/jenkins-slave.sh
@@ -43,7 +43,7 @@
   mkdir -p /home/ci/node
   (cd /home/ci/node && curl "https://nodejs.org/dist/v6.9.1/node-v6.9.1-linux-x64.tar.gz" | tar zx)
   # || true to ignore failure on non-linux platforms.
-  (PATH=/home/ci/node/node-v6.9.1-linux-x64/bin:$PATH npm install -g typescript fried-twinkie || true)
+  (PATH=/home/ci/node/node-v6.9.1-linux-x64/bin:$PATH npm install -g typescript@2.3.4 fried-twinkie@0.0.14 || true)
 fi
 
 cd /home/ci
diff --git a/mac/mac-nodejs.sh b/mac/mac-nodejs.sh
index 6711e29..a7ad2e4 100644
--- a/mac/mac-nodejs.sh
+++ b/mac/mac-nodejs.sh
@@ -22,5 +22,5 @@
 if [ ! -d "/Users/ci/node" ]; then
   mkdir -p "/Users/ci/node"
   (cd "/Users/ci/node" && curl "https://nodejs.org/dist/v6.9.1/node-v6.9.1-darwin-x64.tar.gz" | tar zx)
-  (PATH=/Users/ci/node/node-v6.9.1-darwin-x64/bin:$PATH npm install -g typescript fried-twinkie)
+  (PATH=/Users/ci/node/node-v6.9.1-darwin-x64/bin:$PATH npm install -g typescript@2.3.4 fried-twinkie@0.0.14)
 fi