Run karma with firefox

In addition, as mentioned in
karma-runner/karma-firefox-launcher#106 on WSL
there's a hack in the karma firefox launcher index.js file necessary to
accomodate a wslpath error.

karma.conf.js

@@ -7,7 +7,7 @@ module.exports = function (config) {
     frameworks: ['jasmine', '@angular-devkit/build-angular'],
     plugins: [
       require('karma-jasmine'),
-      require('karma-chrome-launcher'),
+      require('karma-firefox-launcher'),
       require('karma-jasmine-html-reporter'),
       require('karma-coverage-istanbul-reporter'),
       require('@angular-devkit/build-angular/plugins/karma')
@@ -25,7 +25,7 @@ module.exports = function (config) {
     colors: true,
     logLevel: config.LOG_INFO,
     autoWatch: true,
-    browsers: ['Chrome'],
+    browsers: ['FirefoxHeadless'],
     singleRun: false,
     restartOnFileChange: true
   });

package.json

@@ -33,15 +33,16 @@
     "@angular/cli": "~9.1.0",
     "@angular/compiler-cli": "~9.1.0",
     "@angular/language-service": "~9.1.0",
-    "@types/node": "^12.11.1",
     "@types/jasmine": "~3.5.0",
     "@types/jasminewd2": "~2.0.3",
+    "@types/node": "^12.11.1",
     "codelyzer": "^5.1.2",
     "jasmine-core": "~3.5.0",
     "jasmine-spec-reporter": "~4.2.1",
     "karma": "~4.4.1",
     "karma-chrome-launcher": "~3.1.0",
     "karma-coverage-istanbul-reporter": "~2.1.0",
+    "karma-firefox-launcher": "^1.3.0",
     "karma-jasmine": "~3.0.1",
     "karma-jasmine-html-reporter": "^1.4.2",
     "protractor": "~5.4.3",