[x64] Fixed a rounding error on x64 for the Uint64ToF64 conversion.

test/cctest/compiler/value-helper.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_CCTEST_COMPILER_VALUE_HELPER_H_
 #define V8_CCTEST_COMPILER_VALUE_HELPER_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 141 matching lines @@
         0x7fffffff,         0x56123761,         0x7fffff00,
         0x761c4761eeeeeeee, 0x80000000eeeeeeee, 0x88888888dddddddd,
         0xa0000000dddddddd, 0xddddddddaaaaaaaa, 0xe0000000aaaaaaaa,
         0xeeeeeeeeeeeeeeee, 0xfffffffdeeeeeeee, 0xf0000000dddddddd,
         0x007fffffdddddddd, 0x003fffffaaaaaaaa, 0x001fffffaaaaaaaa,
         0x000fffff,         0x0007ffff,         0x0003ffff,
         0x0001ffff,         0x0000ffff,         0x00007fff,
         0x00003fff,         0x00001fff,         0x00000fff,
         0x000007ff,         0x000003ff,         0x000001ff,
         0x00003fffffffffff, 0x00001fffffffffff, 0x00000fffffffffff,
-        0x000007ffffffffff, 0x000003ffffffffff, 0x000001ffffffffff};
+        0x000007ffffffffff, 0x000003ffffffffff, 0x000001ffffffffff,
+        0x8000008000000000, 0x8000008000000001, 0x8000000000000400,
+        0x8000000000000401};
     return std::vector<uint64_t>(&kValues[0], &kValues[arraysize(kValues)]);
   }
 
   static const std::vector<double> nan_vector(size_t limit = 0) {
     static const double nan = std::numeric_limits<double>::quiet_NaN();
     static const double values[] = {-nan,               -V8_INFINITY * -0.0,
                                     -V8_INFINITY * 0.0, V8_INFINITY * -0.0,
                                     V8_INFINITY * 0.0,  nan};
     return std::vector<double>(&values[0], &values[arraysize(values)]);
   }
@@ skipping 22 matching lines @@
 
 #define FOR_INT32_SHIFTS(var) for (int32_t var = 0; var < 32; var++)
 
 #define FOR_UINT32_SHIFTS(var) for (uint32_t var = 0; var < 32; var++)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CCTEST_COMPILER_VALUE_HELPER_H_