message: Improve type of ReadableStreamReader
diff: },
  "ReadableStreamReader": {
  "name": "ReadableStreamReader",
  - "override-exposed": "Window Worker"
  + "override-exposed": "Window Worker",
  + "type-parameters": [
  + {
  + "name": "R",
  + "default": "any"
  + }
  + ],
  + "methods": {
  + "method": {
  + "read": {
  + "name": "read",
  + "override-signatures": [
  + "read(): Promise<ReadableStreamReadResult<R>>"
  + ]
  + }
  + }
  + }
  },
  "ReadableStreamReadResult": {
  "name": "ReadableStreamReadResult",
  