Don't test writing 1 byte 65k times.

tests/standalone/io/process_sync_test.dart

Index: tests/standalone/io/process_sync_test.dart
diff --git a/tests/standalone/io/process_sync_test.dart b/tests/standalone/io/process_sync_test.dart
index 04bc59f11cf1a32f2c59cd134f6eae39f8c8621e..55af8314591b836833f30446f7e149044c2b44c4 100644
--- a/tests/standalone/io/process_sync_test.dart
+++ b/tests/standalone/io/process_sync_test.dart
@@ -50,10 +50,8 @@ main() {
   // The buffer size used in process.h.
   var kBufferSize = 16 * 1024;
   test(1, kBufferSize, kBufferSize, 0);
-  test(1, kBufferSize - 1, kBufferSize + 1, 0);
-  test(kBufferSize - 1, 1, 1, 0);
-  test(kBufferSize, 1, 1, 0);
-  test(kBufferSize + 1, 1, 1, 0);
+  test(1, kBufferSize - 1, kBufferSize - 1, 0);
+  test(1, kBufferSize + 1, kBufferSize + 1, 0);
 
   test(10, 10, 10, 1);
   test(10, 10, 10, 255);