Do not embed is_auto_setup_scope into the compilation of native calls.

runtime/vm/native_entry.h

Index: runtime/vm/native_entry.h
diff --git a/runtime/vm/native_entry.h b/runtime/vm/native_entry.h
index 9b8f6e341e68eceba17ff5802570c6b79a3b6335..187472f4a6372f4d1e2e448cb3cc60a582f3c3ce 100644
--- a/runtime/vm/native_entry.h
+++ b/runtime/vm/native_entry.h
@@ -22,6 +22,18 @@ namespace dart {
 class Class;
 class String;
 
+// We have three variants of native functions:
+//  - bootstrap natives, which are called directly from stub code. The callee is
+//    responsible for safepoint transitions and setting up handle scopes as
+//    needed. Only VM-defined natives are bootstrap natives; they cannot be
+//    defined by embedders or native extensions.
+//  - no scope natives, which are called through a wrapper function. The wrapper
+//    function handles the safepoint transition. The callee is responsible for
+//    setting up API scopes as needed.
+//  - auto scope natives, which are called through a wrapper function. The
+//    wrapper function handles the safepoint transition and sets up an API
+//    scope.
+
 typedef void (*NativeFunction)(NativeArguments* arguments);
 
 
@@ -107,9 +119,13 @@ class NativeEntry : public AllStatic {
                                                uword pc);
   static const uint8_t* ResolveSymbol(uword pc);
 
-  static uword NativeCallWrapperEntry();
-  static void NativeCallWrapper(Dart_NativeArguments args,
-                                Dart_NativeFunction func);
+  static uword NoScopeNativeCallWrapperEntry();
+  static void NoScopeNativeCallWrapper(Dart_NativeArguments args,
+                                       Dart_NativeFunction func);
+
+  static uword AutoScopeNativeCallWrapperEntry();
+  static void AutoScopeNativeCallWrapper(Dart_NativeArguments args,
+                                         Dart_NativeFunction func);
 
 // DBC does not support lazy native call linking.
 #if !defined(TARGET_ARCH_DBC)
@@ -118,8 +134,10 @@ class NativeEntry : public AllStatic {
 #endif
 
  private:
-  static void NativeCallWrapperNoStackCheck(Dart_NativeArguments args,
-                                            Dart_NativeFunction func);
+  static void NoScopeNativeCallWrapperNoStackCheck(Dart_NativeArguments args,
+                                                   Dart_NativeFunction func);
+  static void AutoScopeNativeCallWrapperNoStackCheck(Dart_NativeArguments args,
+                                                     Dart_NativeFunction func);
 
   static bool ReturnValueIsError(NativeArguments* arguments);
   static void PropagateErrors(NativeArguments* arguments);