Fix the js build running out of heap space (#1408)

diff --git a/caravel/assets/package.json b/caravel/assets/package.json
index 1097f0b..cae495c 100644
--- a/caravel/assets/package.json
+++ b/caravel/assets/package.json
@@ -11,7 +11,7 @@
     "test": "npm run lint && mocha --compilers js:babel-core/register --require spec/helpers/browser.js --recursive spec/**/*_spec.*",
     "cover": "babel-node ./node_modules/.bin/istanbul cover _mocha -- --require spec/helpers/browser.js --recursive spec/**/*_spec.*",
     "dev": "NODE_ENV=dev webpack -d --watch --colors --progress",
-    "prod": "NODE_ENV=production webpack -p --colors --progress",
+    "prod": "NODE_ENV=production node --max_old_space_size=8192 ./node_modules/webpack/bin/webpack.js -p --colors --progress",
     "build": "NODE_ENV=production webpack --colors --progress",
     "lint": "eslint --ignore-path=.eslintignore --ext .js,.jsx ."
   },