Port r9428 to 3.5 branch.

src/globals.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 208 matching lines @@
 // IEEE 754 single precision floating point number bit layout.
 const uint32_t kBinary32SignMask = 0x80000000u;
 const uint32_t kBinary32ExponentMask = 0x7f800000u;
 const uint32_t kBinary32MantissaMask = 0x007fffffu;
 const int kBinary32ExponentBias = 127;
 const int kBinary32MaxExponent  = 0xFE;
 const int kBinary32MinExponent  = 0x01;
 const int kBinary32MantissaBits = 23;
 const int kBinary32ExponentShift = 23;
 
+// Quiet NaNs have bits 51 to 62 set, possibly the sign bit, and no
+// other bits set.
+const uint64_t kQuietNaNMask = static_cast<uint64_t>(0xfff) << 51;
+
 // ASCII/UC16 constants
 // Code-point values in Unicode 4.0 are 21 bits wide.
 typedef uint16_t uc16;
 typedef int32_t uc32;
 const int kASCIISize    = kCharSize;
 const int kUC16Size     = sizeof(uc16);      // NOLINT
 const uc32 kMaxAsciiCharCode = 0x7f;
 const uint32_t kMaxAsciiCharCodeU = 0x7fu;
 
 
@@ skipping 79 matching lines @@
 // -----------------------------------------------------------------------------
 // Forward declarations for frequently used classes
 // (sorted alphabetically)
 
 class FreeStoreAllocationPolicy;
 template <typename T, class P = FreeStoreAllocationPolicy> class List;
 
 } }  // namespace v8::internal
 
 #endif  // V8_GLOBALS_H_