Darwin 18 is macOS 10.14.

Change-Id: I70184c0164e9064d9f6d86bd3892ae0100cb4178
Reviewed-on: https://chromium-review.googlesource.com/1105064Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568432}

base/mac/mac_util.mm

@@ -422,7 +422,7 @@ int MacOSXMinorVersionInternal() {
   // immediate death.
   CHECK(darwin_major_version >= 6);
   int mac_os_x_minor_version = darwin_major_version - 4;
-  DLOG_IF(WARNING, darwin_major_version > 17)
+  DLOG_IF(WARNING, darwin_major_version > 18)
       << "Assuming Darwin " << base::IntToString(darwin_major_version)
       << " is macOS 10." << base::IntToString(mac_os_x_minor_version);