[wasm] Int64Lowering of Int64Sub on ia32 and arm.

src/compiler/machine-operator.h

Index: src/compiler/machine-operator.h
diff --git a/src/compiler/machine-operator.h b/src/compiler/machine-operator.h
index a7cb81bf415ccbe8973bddb2708f421a508c00d1..ef48094a58918086780cbd15052870732269fd82 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -180,6 +180,7 @@ class MachineOperatorBuilder final : public ZoneObject {
   const Operator* Word64Equal();
 
   const Operator* Int32PairAdd();
+  const Operator* Int32PairSub();
   const Operator* Word32PairShl();
   const Operator* Word32PairShr();
   const Operator* Word32PairSar();