…ription

* master: (211 commits)
  Update deps (graphql#2844)
  resources: use named groups in RegExp (graphql#2840)
  TS: exclude integration tests from root tsconfig.json (graphql#2838)
  Flow: remove support for measuring Flow coverage (graphql#2837)
  CI: test on node 15 (graphql#2836)
  Update deps (graphql#2835)
  build: add support for experimental releases (graphql#2831)
  15.4.0
  Update deps (graphql#2827)
  Update deps (graphql#2825)
  integrationTests: add Flow test (graphql#2819)
  fix: ensure variance of types matches how values are used (graphql#2786)
  Cleanup '__fixtures__' leftovers (graphql#2818)
  Convert fixtures to be JS files (graphql#2816)
  Update deps (graphql#2815)
  benchmark: extract benchmarks into separate folder and run them on NPM package
  Update deps (graphql#2810)
  Update outdated documentation (graphql#2806)
  Make print() break arguments over multiple lines (graphql#2797)
  Added check for specific symbols in polyfills/symbols (graphql#2804)
  ...