[turbofan] Machine operators are globally shared singletons.

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index 91ae5b2a461ef1f29146c7f94b44237ac7ad4cd1..25cde42670d6d68494f3e1d80024a922758d9e89 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -1924,7 +1924,7 @@ Node* AstGraphBuilder::BuildVariableAssignment(Variable* variable, Node* value,
 
 Node* AstGraphBuilder::BuildLoadObjectField(Node* object, int offset) {
   // TODO(sigurds) Use simplified load here once it is ready.
-  MachineOperatorBuilder machine(zone());
+  MachineOperatorBuilder machine;
   Node* field_load = NewNode(machine.Load(kMachAnyTagged), object,
                              jsgraph_->Int32Constant(offset - kHeapObjectTag));
   return field_load;