[turbofan] remove one level of indirection in phi inputs

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index 75fc35560a18fa80e6a37b549d63ccde0ea19260..105e2550402faba70676a6bc3848f59f17f0ee6e 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -1019,7 +1019,7 @@ void InstructionSelector::VisitPhi(Node* node) {
   for (int i = 0; i < input_count; ++i) {
     Node* const input = node->InputAt(i);
     MarkAsUsed(input);
-    phi->Extend(instruction_zone(), GetVirtualRegister(input));
+    phi->SetInput(static_cast<size_t>(i), GetVirtualRegister(input));
   }
 }