Merge latest changes from http://www.netlib.org/fp/dtoa.c into dtoa.cc

base/strings/string_number_conversions_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/string_number_conversions.h"
 
 #include <errno.h>
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
@@ skipping 763 matching lines @@
     {"\t\n\v\f\r -123.45e2", -12345.0, false},
     {"+123 e4", 123.0, false},
     {"123e ", 123.0, false},
     {"123e", 123.0, false},
     {" 2.99", 2.99, false},
     {"1e3.4", 1000.0, false},
     {"nothing", 0.0, false},
     {"-", 0.0, false},
     {"+", 0.0, false},
     {"", 0.0, false},
+
+    // crbug.org/588726
+    {"-0.0010000000000000000000000000000000000000001e-256",
+     -1.0000000000000001e-259, true},
   };
 
   for (size_t i = 0; i < arraysize(cases); ++i) {
     double output;
     errno = 1;
     EXPECT_EQ(cases[i].success, StringToDouble(cases[i].input, &output));
     if (cases[i].success)
       EXPECT_EQ(1, errno) << i;  // confirm that errno is unchanged.
     EXPECT_DOUBLE_EQ(cases[i].output, output);
   }
@@ skipping 90 matching lines @@
   };
 
   for (const auto& test : cases) {
     double output;
     EXPECT_TRUE(StringToDouble(test.input, &output));
     EXPECT_EQ(bit_cast<uint64_t>(output), test.expected);
   }
 }
 
 }  // namespace base