Remove use of the deprecated mx_current_time Fuchsia syscall

runtime/bin/utils_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 "platform/globals.h"
 #if defined(TARGET_OS_FUCHSIA)
 
 #include <errno.h>
 #include <magenta/syscalls.h>
 #include <magenta/types.h>
@@ skipping 70 matching lines @@
 void TimerUtils::InitOnce() {
 }
 
 
 int64_t TimerUtils::GetCurrentMonotonicMillis() {
   return GetCurrentMonotonicMicros() / 1000;
 }
 
 
 int64_t TimerUtils::GetCurrentMonotonicMicros() {
-  int64_t ticks = mx_current_time();
+  int64_t ticks = mx_time_get(MX_CLOCK_MONOTONIC);
   return ticks / kNanosecondsPerMicrosecond;
 }
 
 
 void TimerUtils::Sleep(int64_t millis) {
   mx_nanosleep(
       millis * kMicrosecondsPerMillisecond * kNanosecondsPerMicrosecond);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_FUCHSIA)