Bug 1420934 - Ensure npm install on netmonitor before installing in…

… webconsole;r=Honza

If the netmonitor hasn't had `npm install` ran, then running the webconsole tests fail,
because the webconsole depends on netmonitor, and the babel plugin "transform-object-rest-spread"
defined in netmonitor/.babelrc cannot be resolved unless if it's been installed.

MozReview-Commit-ID: KyQgja5rRpg

--HG--
extra : rebase_source : 9a8487fccd7c8641f47dcc405be3c8324bf8474c

devtools/client/webconsole/package.json

@@ -5,6 +5,7 @@
     "node": ">=6.9.0"
   },
   "scripts": {
+    "preinstall": "cd ../netmonitor && npm install && cd ../webconsole",
     "start": "cross-env NODE_ENV=production node bin/dev-server",
     "dev": "node bin/dev-server",
     "test": "cross-env NODE_ENV=test NODE_PATH=../../../ mocha new-console-output/test/**/*.test.js --compilers js:babel-register -r jsdom-global/register -r ./new-console-output/test/require-helper.js"