Is Code Coverage broken?

I've tried to run Code Coverage (after installing dependencies of course) but I've got an error.

npm run coverage

vimium@ coverage /path_to_vimium
cake coverage

/path_to_vimium/lib/utils.js:8
if (window.forTrusted == null) {
^

ReferenceError: window is not defined
at Object. (/path_to_vimium/lib/utils.js:8:3)
at Object. (/path_to_vimium/lib/utils.js:492:4)
at Module._compile (module.js:662:30)
at Object.Module._extensions..js (module.js:673:10)
at Module.load (/path_to_vimium/node_modules/coffeescript/lib/coffee-script/register.js:45:36)
at tryModuleLoad (module.js:515:12)
at Function.Module._load (module.js:507:3)
at Module.require (module.js:606:17)
at require (internal/module.js:11:18)
at Object.action (/path_to_vimium/Cakefile:202:13)
at invoke (/path_to_vimium/node_modules/coffeescript/lib/coffee-script/cake.js:44:26)
at Object.exports.run (/path_to_vimium/node_modules/coffeescript/lib/coffee-script/cake.js:70:20)
at Object. (/path_to_vimium/node_modules/coffeescript/bin/cake:15:42)
at Module._compile (module.js:662:30)
at Object.Module._extensions..js (module.js:673:10)
at Module.load (module.js:575:32)
at tryModuleLoad (module.js:515:12)
at Function.Module._load (module.js:507:3)
at Function.Module.runMain (module.js:703:10)
at startup (bootstrap_node.js:193:16)
at bootstrap_node.js:665:3

Start by running npm run coverage and inspect Cakefile around line 202 and lib/utils.js around line 8 to trace why coverage loads browser code without window. Done means npm run coverage completes without the ReferenceError: window is not defined.