Array() in optimized code can create with wrong ElementsKind in corner cases.

src/arm64/lithium-codegen-arm64.cc

Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index d91c2ca58f66547f0900568d37a888b4e3807977..78f46201a176c85baf419c8db39a3d6ed2889117 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -460,7 +460,15 @@ void LCodeGen::DoCallNewArray(LCallNewArray* instr) {
   DCHECK(ToRegister(instr->constructor()).is(x1));
 
   __ Mov(x0, Operand(instr->arity()));
-  __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
+  if (instr->arity() == 1) {
+    // We only need the allocation site for the case we have a length argument.
+    // The case may bail out to the runtime, which will determine the correct
+    // elements kind with the site.
+    __ Mov(x2, instr->hydrogen()->site());
+  } else {
+    __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
+  }
+
 
   ElementsKind kind = instr->hydrogen()->elements_kind();
   AllocationSiteOverrideMode override_mode =