[builtins] Introduce proper Float64Log2 and Float64Log10 operators.

src/compiler/machine-operator-reducer.cc

Index: src/compiler/machine-operator-reducer.cc
diff --git a/src/compiler/machine-operator-reducer.cc b/src/compiler/machine-operator-reducer.cc
index dddf14d0b081afec940f90ee9574f8b6dbfe4712..54ac61777599f85b2c93957c8328365f412c8dee 100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -412,6 +412,16 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
       if (m.HasValue()) return ReplaceFloat64(base::ieee754::log1p(m.Value()));
       break;
     }
+    case IrOpcode::kFloat64Log2: {
+      Float64Matcher m(node->InputAt(0));
+      if (m.HasValue()) return ReplaceFloat64(base::ieee754::log2(m.Value()));
+      break;
+    }
+    case IrOpcode::kFloat64Log10: {
+      Float64Matcher m(node->InputAt(0));
+      if (m.HasValue()) return ReplaceFloat64(base::ieee754::log10(m.Value()));
+      break;
+    }
     case IrOpcode::kChangeFloat32ToFloat64: {
       Float32Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceFloat64(m.Value());