Take output type into account in JSTypedLowering reduction.

src/compiler/opcodes.h

Index: src/compiler/opcodes.h
diff --git a/src/compiler/opcodes.h b/src/compiler/opcodes.h
index e210abd6b96394c4f53188b44789ae9d05667410..944f646a4893ec30a361546238179fefdc79e486 100644
--- a/src/compiler/opcodes.h
+++ b/src/compiler/opcodes.h
@@ -289,6 +289,20 @@ class IrOpcode {
     }
   }
 
+
+  static bool IsLeafOpcode(Value val) {
+    switch (val) {
+#define RETURN_NAME(x) \
+  case k##x:           \
+    return true;
+      LEAF_OP_LIST(RETURN_NAME)
+#undef RETURN_NAME
+      default:
+        return false;
+    }
+  }
+
+
   static bool IsCommonOpcode(Value val) {
     switch (val) {
 #define RETURN_NAME(x) \