nyc: Switch config from JSON to YAML and move args from package.json

.nycrc.yml

@@ -0,0 +1,8 @@
+include:
+  - "src/"
+exclude:
+  - "src/polyfills"
+clean: true
+temp-directory: "coverage"
+skip-full: true
+reporter: [json, html, text]

package.json

@@ -26,7 +26,7 @@
     "test": "npm run lint && npm run check && npm run testonly",
     "test:ci": "npm run lint -- --no-cache && npm run check && npm run testonly:cover",
     "testonly": "mocha --full-trace src/**/__tests__/**/*-test.js",
-    "testonly:cover": "nyc --clean --skip-full --reporter json --reporter html --reporter text -- npm run testonly",
+    "testonly:cover": "nyc npm run testonly",
     "lint": "eslint --cache --report-unused-disable-directives src",
     "benchmark": "node ./resources/benchmark.js",
     "prettier": "prettier --write --list-different 'src/**/*.js'",