Reintroduce duplicate identifier detection in preparser.

src/platform.h

Index: src/platform.h
diff --git a/src/platform.h b/src/platform.h
index 6b2348c8903f4eabcbb2455283793688ada56844..034fe3404ded4d1f69abe6724a17ff3b6ad7b2f8 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -44,7 +44,22 @@
 #ifndef V8_PLATFORM_H_
 #define V8_PLATFORM_H_
 
-#define V8_INFINITY INFINITY
+#ifdef __sun
+# ifndef signbit
+int signbit(double x);
+# endif
+#endif
+
+// GCC specific stuff
+#ifdef __GNUC__
+
+// Needed for va_list on at least MinGW and Android.
+#include <stdarg.h>
+
+#define __GNUC_VERSION__ (__GNUC__ * 10000 + __GNUC_MINOR__ * 100)
+
+#endif  // __GNUC__
+
 
 // Windows specific stuff.
 #ifdef WIN32
@@ -52,27 +67,7 @@
 // Microsoft Visual C++ specific stuff.
 #ifdef _MSC_VER
 
-enum {
-  FP_NAN,
-  FP_INFINITE,
-  FP_ZERO,
-  FP_SUBNORMAL,
-  FP_NORMAL
-};
-
-#undef V8_INFINITY
-#define V8_INFINITY HUGE_VAL
-
-namespace v8 {
-namespace internal {
-int isfinite(double x);
-} }
-int isnan(double x);
-int isinf(double x);
-int isless(double x, double y);
-int isgreater(double x, double y);
-int fpclassify(double x);
-int signbit(double x);
+#include "win32-math.h"
 
 int strncasecmp(const char* s1, const char* s2, int n);
 
@@ -83,36 +78,6 @@ int random();
 
 #endif  // WIN32
 
-
-#ifdef __sun
-# ifndef signbit
-int signbit(double x);
-# endif
-#endif
-
-
-// GCC specific stuff
-#ifdef __GNUC__
-
-// Needed for va_list on at least MinGW and Android.
-#include <stdarg.h>
-
-#define __GNUC_VERSION__ (__GNUC__ * 10000 + __GNUC_MINOR__ * 100)
-
-// Unfortunately, the INFINITY macro cannot be used with the '-pedantic'
-// warning flag and certain versions of GCC due to a bug:
-// http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11931
-// For now, we use the more involved template-based version from <limits>, but
-// only when compiling with GCC versions affected by the bug (2.96.x - 4.0.x)
-// __GNUC_PREREQ is not defined in GCC for Mac OS X, so we define our own macro
-#if __GNUC_VERSION__ >= 29600 && __GNUC_VERSION__ < 40100
-#include <limits>
-#undef V8_INFINITY
-#define V8_INFINITY std::numeric_limits<double>::infinity()
-#endif
-
-#endif  // __GNUC__
-
 #include "atomicops.h"
 #include "platform-tls.h"
 #include "utils.h"