[fuchsia] Use new mx_deadline_after interface

runtime/vm/os_fuchsia.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(HOST_OS_FUCHSIA)
 
 #include "vm/os.h"
 
 #include <errno.h>
@@ skipping 144 matching lines @@
 }
 
 
 uintptr_t OS::MaxRSS() {
   // TODO(US-95): Implement.
   return 0;
 }
 
 
 void OS::Sleep(int64_t millis) {
-  mx_nanosleep(millis * kMicrosecondsPerMillisecond *
-               kNanosecondsPerMicrosecond);
+  SleepMicros(millis * kMicrosecondsPerMillisecond);
 }
 
 
 void OS::SleepMicros(int64_t micros) {
-  mx_nanosleep(micros * kNanosecondsPerMicrosecond);
+  mx_nanosleep(mx_deadline_after(micros * kNanosecondsPerMicrosecond));
 }
 
 
 void OS::DebugBreak() {
   UNIMPLEMENTED();
 }
 
 
 uintptr_t DART_NOINLINE OS::GetProgramCounter() {
   return reinterpret_cast<uintptr_t>(
@@ skipping 129 matching lines @@
 }
 
 
 void OS::Exit(int code) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #endif  // defined(HOST_OS_FUCHSIA)