Support Smi->Double->HeapObject transitions in constructed Arrays.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index e423ae3a4f6aad6acbf048f974c959fd9718e04c..1719496c85ffc55c31b805c699c15cf7742bcbfd 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -1305,6 +1305,9 @@ static void ArrayNativeCode(MacroAssembler* masm,
   __ jmp(&entry);
   __ bind(&loop);
   __ movq(kScratchRegister, Operand(r9, rcx, times_pointer_size, 0));
+  if (FLAG_smi_only_arrays) {
+    __ JumpIfNotSmi(kScratchRegister, call_generic_code);
+  }
   __ movq(Operand(rdx, 0), kScratchRegister);
   __ addq(rdx, Immediate(kPointerSize));
   __ bind(&entry);