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

base/strings/string_number_conversions_unittest.cc

Index: base/strings/string_number_conversions_unittest.cc
diff --git a/base/strings/string_number_conversions_unittest.cc b/base/strings/string_number_conversions_unittest.cc
index 0576302a0798c98329531d27370a9bd15488ebdf..6b2bd97da9a63b49e17c9201e9cdc9d335bda40d 100644
--- a/base/strings/string_number_conversions_unittest.cc
+++ b/base/strings/string_number_conversions_unittest.cc
@@ -781,6 +781,10 @@ TEST(StringNumberConversionsTest, StringToDouble) {
     {"-", 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) {