Make sure double to int conversion is correct.

test/cctest/test-utils.cc

 // 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 37 matching lines @@
   CHECK_EQ(0, FastD2I(0.345));
   CHECK_EQ(1, FastD2I(1.234));
   CHECK_EQ(1000000, FastD2I(1000000.123));
   // Check that >> is implemented as arithmetic shift right.
   // If this is not true, then ArithmeticShiftRight() must be changed,
   // There are also documented right shifts in assembler.cc of
   // int8_t and intptr_t signed integers.
   CHECK_EQ(-2, -8 >> 2);
   CHECK_EQ(-2, static_cast<int8_t>(-8) >> 2);
   CHECK_EQ(-2, static_cast<int>(static_cast<intptr_t>(-8) >> 2));
+
+  CHECK_EQ(-1000000, FastD2IChecked(-1000000.0));
+  CHECK_EQ(-1, FastD2IChecked(-1.0));
+  CHECK_EQ(0, FastD2IChecked(0.0));
+  CHECK_EQ(1, FastD2IChecked(1.0));
+  CHECK_EQ(1000000, FastD2IChecked(1000000.0));
+
+  CHECK_EQ(-1000000, FastD2IChecked(-1000000.123));
+  CHECK_EQ(-1, FastD2IChecked(-1.234));
+  CHECK_EQ(0, FastD2IChecked(0.345));
+  CHECK_EQ(1, FastD2IChecked(1.234));
+  CHECK_EQ(1000000, FastD2IChecked(1000000.123));
+
+  CHECK_EQ(INT_MAX, FastD2IChecked(1.0e100));
+  CHECK_EQ(INT_MIN, FastD2IChecked(-1.0e100));
+  CHECK_EQ(INT_MIN, FastD2IChecked(NAN));
 }
 
 
 TEST(SNPrintF) {
   // Make sure that strings that are truncated because of too small
   // buffers are zero-terminated anyway.
   const char* s = "the quick lazy .... oh forget it!";
   int length = StrLength(s);
   for (int i = 1; i < length * 2; i++) {
     static const char kMarker = static_cast<char>(42);
@@ skipping 132 matching lines @@
 TEST(SequenceCollectorRegression) {
   SequenceCollector<char> collector(16);
   collector.StartSequence();
   collector.Add('0');
   collector.AddBlock(
       i::Vector<const char>("12345678901234567890123456789012", 32));
   i::Vector<char> seq = collector.EndSequence();
   CHECK_EQ(0, strncmp("0123456789012345678901234567890123",
                       seq.start(), seq.length()));
 }