fix: properly initialize Firefox Aurora & Nightly.
fix: properly initialize Firefox Aurora & Nightly.

The signature of the FirefoxBrowser constructor has changed, causing
Aurora & Nightly constructors to fail. Instead of manually passing
all parameters along, it’s better to use `apply` on the whole
arguments object.

nishant8BITS/karma-firefox-launcher,karma-runner/karma-firefox-launcher,oyiptong/karma-firefox-launcher,karma-runner/karma-firefox-launcher,jamestalmage/karma-firefox-launcher