Merged r16082 into 3.19 branch.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 496dc88cb61a79faf599f3fdeb5d08eeada7b13a..9098571bd3f31a03b6a5fbcb9712addac8b405bd 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -4480,10 +4480,7 @@ static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
   } else if (index->IsSub()) {
     sign = -1;
     HSub* sub = HSub::cast(index);
-    if (sub->left()->IsConstant()) {
-      subexpression = sub->right();
-      constant = HConstant::cast(sub->left());
-    } else if (sub->right()->IsConstant()) {
+    if (sub->right()->IsConstant()) {
       subexpression = sub->left();
       constant = HConstant::cast(sub->right());
     } else {