Port r9428 to 3.5 branch.

src/v8globals.h

Index: src/v8globals.h
diff --git a/src/v8globals.h b/src/v8globals.h
index aff27579f8d78b6cd8337f9b8fba578237993c42..f05a702e1a137dee0a9588482a68875c64288c7f 100644
--- a/src/v8globals.h
+++ b/src/v8globals.h
@@ -98,10 +98,6 @@ const int kPageSizeBits = 13;
 const int kProcessorCacheLineSize = 64;
 
 // Constants relevant to double precision floating point numbers.
-
-// 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;
 // If looking only at the top 32 bits, the QNaN mask is bits 19 to 30.
 const uint32_t kQuietNaNHighBitsMask = 0xfff << (51 - 32);