Use #if TARGET_OS_IOS instead of #ifdef TARGET_OS_IOS.

runtime/bin/platform_macos.cc

 // Copyright (c) 2012, 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_MACOS)
 
 #include <mach-o/dyld.h>
 #include <sys/types.h>
 #include <sys/sysctl.h>
 
 #include "bin/file.h"
 #include "bin/platform.h"
 
-#if !defined(TARGET_OS_IOS)
+#if !TARGET_OS_IOS
 #include <crt_externs.h>  // NOLINT
-#endif  // !defined(TARGET_OS_IOS)
+#endif  // !TARGET_OS_IOS
 #include <signal.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "bin/fdutils.h"
 
 
 namespace dart {
 namespace bin {
 
@@ skipping 33 matching lines @@
   return "dylib";
 }
 
 
 bool Platform::LocalHostname(char *buffer, intptr_t buffer_length) {
   return gethostname(buffer, buffer_length) == 0;
 }
 
 
 char** Platform::Environment(intptr_t* count) {
-#if defined(TARGET_OS_IOS)
+#if TARGET_OS_IOS
   // TODO(iposva): On Mac (desktop), _NSGetEnviron() is used to access the
   // environ from shared libraries or bundles. This is present in crt_externs.h
   // which is unavailable on iOS. On iOS, everything is statically linked for
   // now. So arguably, accessing the environ directly with a "extern char
   // **environ" will work. But this approach is brittle as the target with this
   // CU could be a dynamic framework (introduced in iOS 8). A more elegant
   // approach needs to be devised.
   return NULL;
 #else
   // Using environ directly is only safe as long as we do not
@@ skipping 35 matching lines @@
   // Return the canonical path as the returned path might contain symlinks.
   char* canon_path = File::GetCanonicalPath(path);
   free(path);
   return canon_path;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)