Add ESLint rule: no-unused-expressions
Add ESLint rule: no-unused-expressions

ppker/backbone,moimikey/backbone,moimikey/backbone,darrrk/backbone,jashkenas/backbone,lastjune/backbone,jashkenas/backbone,zgl2007dj/backbone,craigmichaelmartin/backbone,akre54/backbone,akre54/backbone,platinumazure/backbone,craigmichaelmartin/backbone,lastjune/backbone,platinumazure/backbone,jridgewell/backbone,ppker/backbone,darrrk/backbone,zgl2007dj/backbone,jridgewell/backbone