Upgrade Flow in fbsource

packages/react-native/Libraries/Blob/FileReader.js

@@ -133,6 +133,7 @@ class FileReader extends EventTarget {
         const base64 = text.split(',')[1];
         const typedArray = toByteArray(base64);
 
+        // $FlowFixMe[incompatible-type]
         this._result = typedArray.buffer;
         this._setReadyState(DONE);
       },

packages/react-native/Libraries/Utilities/__tests__/binaryToBase64-itest.js

@@ -21,6 +21,7 @@ describe('binaryToBase64', () => {
   it('should encode an ArrayBuffer', () => {
     const bytes = new TextEncoder().encode('Test string');
 
+    // $FlowFixMe[incompatible-type]
     expect(decodeBase64(binaryToBase64(bytes.buffer))).toEqual(
       Array.from(bytes),
     );

packages/react-native/Libraries/WebSocket/WebSocket.js

@@ -246,6 +246,7 @@ class WebSocket extends EventTarget {
         let data: Blob | BlobData | ArrayBuffer | string = ev.data;
         switch (ev.type) {
           case 'binary':
+            // $FlowFixMe[incompatible-type]
             data = base64.toByteArray(ev.data).buffer;
             break;
           case 'blob':

packages/react-native/Libraries/WebSocket/WebSocketInterceptor.js

@@ -244,6 +244,7 @@ const WebSocketInterceptor = {
     ) {
       return `ArrayBuffer {${String(Array.from(new Uint8Array(value)))}}`;
     }
+    // $FlowFixMe[incompatible-type]
     return value;
   },