Install eslint-plugin-promise in jenkins-docker images

Change-Id: I2d74ce24362c01387ece42fe29777c06939980bb
diff --git a/jenkins-docker/slave-node-wct/Dockerfile b/jenkins-docker/slave-node-wct/Dockerfile
index 5c3ec96..842f8c0 100644
--- a/jenkins-docker/slave-node-wct/Dockerfile
+++ b/jenkins-docker/slave-node-wct/Dockerfile
@@ -15,6 +15,7 @@
       eslint@"=4.19.0" \
       eslint-config-google@"=0.12.0" \
       eslint-plugin-html@"=5.0.3" \
+      eslint-plugin-promise@"=4.0.1" \
       typescript \
       fried-twinkie@">0.2.0" \
       polylint polymer-cli