Remove unused defaultWatchFileKind method since useFsEvents is default for tsserver and tsc (#51044)

src/compiler/sys.ts

@@ -854,7 +854,6 @@ namespace ts {
         tscWatchFile: string | undefined;
         useNonPollingWatchers?: boolean;
         tscWatchDirectory: string | undefined;
-        defaultWatchFileKind: System["defaultWatchFileKind"];
         inodeWatching: boolean;
         sysLog: (s: string) => void;
     }
@@ -875,7 +874,6 @@ namespace ts {
         tscWatchFile,
         useNonPollingWatchers,
         tscWatchDirectory,
-        defaultWatchFileKind,
         inodeWatching,
         sysLog,
     }: CreateSystemWatchFunctions): { watchFile: HostWatchFile; watchDirectory: HostWatchDirectory; } {
@@ -953,8 +951,8 @@ namespace ts {
                     return useNonPollingWatchers ?
                         // Use notifications from FS to watch with falling back to fs.watchFile
                         generateWatchFileOptions(WatchFileKind.UseFsEventsOnParentDirectory, PollingWatchKind.PriorityInterval, options) :
-                        // Default to do not use fixed polling interval
-                        { watchFile: defaultWatchFileKind?.() || WatchFileKind.UseFsEvents };
+                        // Default to using fs events
+                        { watchFile: WatchFileKind.UseFsEvents };
             }
         }
 
@@ -1380,7 +1378,6 @@ namespace ts {
         base64encode?(input: string): string;
         /*@internal*/ bufferFrom?(input: string, encoding?: string): Buffer;
         /*@internal*/ require?(baseDir: string, moduleName: string): RequireResult;
-        /*@internal*/ defaultWatchFileKind?(): WatchFileKind | undefined;
 
         // For testing
         /*@internal*/ now?(): Date;
@@ -1473,7 +1470,6 @@ namespace ts {
                 tscWatchFile: process.env.TSC_WATCHFILE,
                 useNonPollingWatchers: process.env.TSC_NONPOLLING_WATCHER,
                 tscWatchDirectory: process.env.TSC_WATCHDIRECTORY,
-                defaultWatchFileKind: () => sys!.defaultWatchFileKind?.(),
                 inodeWatching: isLinuxOrMacOs,
                 sysLog,
             });

src/harness/virtualFileSystemWithWatch.ts

@@ -350,7 +350,6 @@ interface Array<T> { length: number; [n: number]: T; }`
         private readonly executingFilePath: string;
         private readonly currentDirectory: string;
         public require: ((initialPath: string, moduleName: string) => RequireResult) | undefined;
-        public defaultWatchFileKind?: () => WatchFileKind | undefined;
         public storeFilesChangingSignatureDuringEmit = true;
         watchFile: HostWatchFile;
         private inodeWatching: boolean | undefined;
@@ -398,7 +397,6 @@ interface Array<T> { length: number; [n: number]: T; }`
                 realpath: this.realpath.bind(this),
                 tscWatchFile,
                 tscWatchDirectory,
-                defaultWatchFileKind: () => this.defaultWatchFileKind?.(),
                 inodeWatching: !!this.inodeWatching,
                 sysLog: s => this.write(s + this.newLine),
             });

src/testRunner/unittests/tscWatch/watchEnvironment.ts

@@ -120,36 +120,6 @@ namespace ts.tscWatch {
             ]
         });
 
-        verifyTscWatch({
-            scenario,
-            subScenario: "watchFile/setting default as fixed chunk size watch file works",
-            commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json"],
-            sys: () => {
-                const configFile: File = {
-                    path: "/a/b/tsconfig.json",
-                    content: "{}"
-                };
-                const files = [libFile, commonFile1, commonFile2, configFile];
-                const sys = createWatchedSystem(files);
-                sys.defaultWatchFileKind = () => WatchFileKind.FixedChunkSizePolling;
-                return sys;
-            },
-            changes: [
-                {
-                    caption: "Make change to file but should detect as changed and schedule program update",
-                    // Make a change to file
-                    change: sys => sys.writeFile(commonFile1.path, "var zz30 = 100;"),
-                    timeouts: checkSingleTimeoutQueueLengthAndRun,
-                },
-                {
-                    caption: "Callbacks: queue and scheduled program update",
-                    change: noop,
-                    // Callbacks: scheduled program update and queue for the polling
-                    timeouts: sys => sys.checkTimeoutQueueLengthAndRun(2),
-                },
-            ]
-        });
-
         describe("tsc-watch when watchDirectories implementation", () => {
             function verifyRenamingFileInSubFolder(subScenario: string, tscWatchDirectory: Tsc_WatchDirectory) {
                 const projectFolder = "/a/username/project";