address code review feedback

Author: adamsitnik

src/libraries/System.IO.FileSystem/tests/File/ReadWriteAllBytesAsync.cs

@@ -73,31 +73,31 @@ public Task AlreadyCanceledAsync()
         [Fact]
         [OuterLoop]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/45954", TestPlatforms.Browser)]
-        public Task ReadFileOver2GBAsync()
+        public async Task ReadFileOver2GBAsync()
         {
             string path = GetTestFilePath();
             using (FileStream fs = File.Create(path))
             {
                 fs.SetLength(int.MaxValue + 1L);
             }
 
-            // File is too large for ReadAllBytes at once
-            return Assert.ThrowsAsync<IOException>(async () => await File.ReadAllBytesAsync(path));
+            // File is too large for ReadAllBytesAsync at once
+            await Assert.ThrowsAsync<IOException>(async () => await File.ReadAllBytesAsync(path));
         }
 
         [Fact]
         [OuterLoop]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/45954", TestPlatforms.Browser)]
-        public Task MaxArrayLengthAsync()
+        public async Task ReadFileOverMaxArrayLengthAsync()
         {
             string path = GetTestFilePath();
             using (FileStream fs = File.Create(path))
             {
                 fs.SetLength(Array.MaxLength + 1L);
             }
 
-            // File is too large for ReadAllBytes at once
-            return Assert.ThrowsAsync<IOException>(async () => await File.ReadAllBytesAsync(path));
+            // File is too large for ReadAllBytesAsync at once
+            await Assert.ThrowsAsync<IOException>(async () => await File.ReadAllBytesAsync(path));
         }
 
         [Fact]

src/libraries/System.Private.CoreLib/src/System/IO/File.cs

@@ -526,7 +526,7 @@ private static async Task<string> InternalReadAllTextAsync(string path, Encoding
             }
 
             // SequentialScan is a perf hint that requires extra sys-call on non-Windows OSes.
-            FileOptions options = (OperatingSystem.IsWindows() ? FileOptions.SequentialScan : FileOptions.None) | FileOptions.Asynchronous;
+            FileOptions options = FileOptions.Asynchronous | (OperatingSystem.IsWindows() ? FileOptions.SequentialScan : FileOptions.None);
             SafeFileHandle sfh = OpenHandle(path, FileMode.Open, FileAccess.Read, FileShare.Read, options);
 
             long fileLength = 0L;