Move WEBCORE_NAVIGATOR macros defaults from the build system into a cpp file.

Source/core/page/NavigatorID.cpp

Index: Source/core/page/NavigatorID.cpp
diff --git a/Source/core/page/NavigatorID.cpp b/Source/core/page/NavigatorID.cpp
index 54363323ad913435bcf0baea6c596947b5942890..85524f0717ad42b08ca23f5ee0dc647092cd7255 100644
--- a/Source/core/page/NavigatorID.cpp
+++ b/Source/core/page/NavigatorID.cpp
@@ -35,7 +35,7 @@
 #include "core/page/NavigatorBase.h"
 #include "wtf/CPU.h"
 
-#if OS(LINUX)
+#if !defined(WEBCORE_NAVIGATOR_PLATFORM) && OS(POSIX) && !OS(MACOSX)
 #include "wtf/StdLibExtras.h"
 #include <sys/utsname.h>
 #endif
@@ -67,14 +67,16 @@ String NavigatorID::platform(const NavigatorBase*)
 {
 #if defined(WEBCORE_NAVIGATOR_PLATFORM)
     return WEBCORE_NAVIGATOR_PLATFORM;
-#else
-#if OS(LINUX)
+#elif OS(MACOSX)
+    // Match Safari and Mozilla on Mac x86.
+    return "MacIntel";
+#elif OS(WIN)
+    // Match Safari and Mozilla on Windows.
+    return "Win32";
+#else // Unix-like systems
     struct utsname osname;
     DEFINE_STATIC_LOCAL(String, platformName, (uname(&osname) >= 0 ? String(osname.sysname) + String(" ") + String(osname.machine) : emptyString()));
     return platformName;
-#else
-#error Non-Linux ports must define WEBCORE_NAVIGATOR_PLATFORM.
-#endif
 #endif
 }