Bug 1256768 - Fix ESLint errors/warnings in...

Bug 1256768 - Fix ESLint errors/warnings in devtools/client/webconsole/console-output.js r=nchevobbe

MozReview-Commit-ID: 76jPTnoqWq7

--HG--
extra : rebase_source : 4bb78c07caccfff16796dbbcf5b56092cb9a300a

.eslintignore

@@ -121,7 +121,6 @@ devtools/client/storage/test/*.html
 devtools/client/webaudioeditor/**
 devtools/client/webconsole/net/**
 devtools/client/webconsole/test/**
-devtools/client/webconsole/console-output.js
 devtools/client/webconsole/hudservice.js
 devtools/client/webconsole/webconsole-connection-proxy.js
 devtools/client/webconsole/webconsole.js