[builtins] Introduce proper Float64Log2 and Float64Log10 operators.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 432c3a1c7b7c547fb5b7809ea9262a198327f2a9..2332408f167e18d048ea72b2a0874877e5641d13 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -1638,6 +1638,16 @@ ExternalReference ExternalReference::ieee754_log1p_function(Isolate* isolate) {
       Redirect(isolate, FUNCTION_ADDR(base::ieee754::log1p), BUILTIN_FP_CALL));
 }
 
+ExternalReference ExternalReference::ieee754_log2_function(Isolate* isolate) {
+  return ExternalReference(
+      Redirect(isolate, FUNCTION_ADDR(base::ieee754::log2), BUILTIN_FP_CALL));
+}
+
+ExternalReference ExternalReference::ieee754_log10_function(Isolate* isolate) {
+  return ExternalReference(
+      Redirect(isolate, FUNCTION_ADDR(base::ieee754::log10), BUILTIN_FP_CALL));
+}
+
 ExternalReference ExternalReference::math_exp_constants(int constant_index) {
   DCHECK(math_exp_data_initialized);
   return ExternalReference(