Remove 1.js, 2.js, 3.js and 4.js

[brunolemos]

• 1.js, 2.js and 3.js are correct on both
  • TypeScript 1.x is ~1,5 year old and should not be considered anymore
  • strictNullChecks is expected to be enabled by default in these comparisons
• 4.js is misleading, should not use enum for that in typescript (4.js is misleading #14)
• Only 5.js, 6.js and 7.js have valid differences between flow and typescript