[turbofan] Introduce a SpeculativeToNumber operator.

src/compiler/typed-optimization.cc

Index: src/compiler/typed-optimization.cc
diff --git a/src/compiler/typed-optimization.cc b/src/compiler/typed-optimization.cc
index 76ae9d48ec1b714066c539c5451eb89fe327e8ba..6c958bdac49b6fa5f8f27bf92ef5d23ce4a59b98 100644
--- a/src/compiler/typed-optimization.cc
+++ b/src/compiler/typed-optimization.cc
@@ -96,6 +96,8 @@ Reduction TypedOptimization::Reduce(Node* node) {
       return ReduceReferenceEqual(node);
     case IrOpcode::kSelect:
       return ReduceSelect(node);
+    case IrOpcode::kSpeculativeToNumber:
+      return ReduceSpeculativeToNumber(node);
     default:
       break;
   }
@@ -311,6 +313,18 @@ Reduction TypedOptimization::ReduceSelect(Node* node) {
   return NoChange();
 }
 
+Reduction TypedOptimization::ReduceSpeculativeToNumber(Node* node) {
+  DCHECK_EQ(IrOpcode::kSpeculativeToNumber, node->opcode());
+  Node* const input = NodeProperties::GetValueInput(node, 0);
+  Type* const input_type = NodeProperties::GetType(input);
+  if (input_type->Is(Type::Number())) {
+    // SpeculativeToNumber(x:number) => x
+    ReplaceWithValue(node, input);
+    return Replace(input);
+  }
+  return NoChange();
+}
+
 Factory* TypedOptimization::factory() const { return isolate()->factory(); }
 
 Graph* TypedOptimization::graph() const { return jsgraph()->graph(); }