Use CallBootstrapC stub for leaf native calls.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
diff --git a/runtime/vm/intermediate_language_x64.cc b/runtime/vm/intermediate_language_x64.cc
index f999bddfbcdc320f15ba3c5fa5d488e672545a59..d7b162da13f103154057e182eff5e63f8c070387 100644
--- a/runtime/vm/intermediate_language_x64.cc
+++ b/runtime/vm/intermediate_language_x64.cc
@@ -734,13 +734,16 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     __ leaq(RAX,
             Address(RBP, kFirstLocalSlotFromFp * kWordSize));
   }
+  const intptr_t argc_tag = NativeArguments::ComputeArgcTag(function());
+  const bool is_leaf_call =
+    (argc_tag & NativeArguments::AutoSetupScopeMask()) == 0;
   __ LoadImmediate(
       RBX, Immediate(reinterpret_cast<uword>(native_c_function())), PP);
   __ LoadImmediate(
-      R10, Immediate(NativeArguments::ComputeArgcTag(function())), PP);
-  const ExternalLabel* stub_entry =
-      (is_bootstrap_native()) ? &StubCode::CallBootstrapCFunctionLabel() :
-                                &StubCode::CallNativeCFunctionLabel();
+      R10, Immediate(argc_tag), PP);
+  const ExternalLabel* stub_entry = (is_bootstrap_native() || is_leaf_call) ?
+      &StubCode::CallBootstrapCFunctionLabel() :
+      &StubCode::CallNativeCFunctionLabel();
   compiler->GenerateCall(token_pos(),
                          stub_entry,
                          PcDescriptors::kOther,