[turbofan] Fix Math.sign.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 73c8af667b8595923a2a725f79fdaf9d6c91f234..799ab1b23249c314744315de3f836df6b64d0c0d 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -2849,7 +2849,7 @@ Node* SimplifiedLowering::Float64Sign(Node* const node) {
       graph()->NewNode(
           common()->Select(MachineRepresentation::kFloat64),
           graph()->NewNode(machine()->Float64LessThan(), zero, input), one,
-          zero));
+          input));
 }
 
 Node* SimplifiedLowering::Int32Abs(Node* const node) {