[builtins] Introduce proper Float64Log2 and Float64Log10 operators.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 63dd1f078b62a20ac0b8c23cded073f10f3a5d10..57f3e68a8ae905be3a4c0bbd2ce9d8a224cf6c8a 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1685,6 +1685,8 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
         SimpleInstallFunction(math, "log", Builtins::kMathLog, 1, true);
     native_context()->set_math_log(*math_log);
     SimpleInstallFunction(math, "log1p", Builtins::kMathLog1p, 1, true);
+    SimpleInstallFunction(math, "log2", Builtins::kMathLog2, 1, true);
+    SimpleInstallFunction(math, "log10", Builtins::kMathLog10, 1, true);
     SimpleInstallFunction(math, "max", Builtins::kMathMax, 2, false);
     SimpleInstallFunction(math, "min", Builtins::kMathMin, 2, false);
     SimpleInstallFunction(math, "round", Builtins::kMathRound, 1, true);