[Math builtins]: Cleanup in ieee754, restoring MSUN version of log2().

test/unittests/base/ieee754-unittest.cc

Index: test/unittests/base/ieee754-unittest.cc
diff --git a/test/unittests/base/ieee754-unittest.cc b/test/unittests/base/ieee754-unittest.cc
index 7246ece3459f45ae092b9a79f2a554a41cb542e1..a0bcad8d35de3baa0a887f27acd8d9d21e637694 100644
--- a/test/unittests/base/ieee754-unittest.cc
+++ b/test/unittests/base/ieee754-unittest.cc
@@ -133,6 +133,7 @@ TEST(Ieee754, Log10) {
   EXPECT_EQ(3.7389561269540406, log10(5482.2158));
   EXPECT_EQ(14.661551142893833, log10(458723662312872.125782332587));
   EXPECT_EQ(-0.9083828622192334, log10(0.12348583358871));
+  EXPECT_EQ(5.0, log10(100000.0));
 }
 
 }  // namespace ieee754