[simulator] Make SimulatorBase::VariadicCall protected

Even though most compilers accept the method to be private, gcc 4.8
complains about this (which seems to be correct). Thus we make this
method protected.

R=franzih@chromium.org

Change-Id: Ia49b2ddebe1ced7529d4943107a76a909c355b73
Reviewed-on: https://chromium-review.googlesource.com/890449Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50931}

src/simulator-base.h

@@ -32,15 +32,7 @@ class SimulatorBase {
   static Redirection* redirection() { return redirection_; }
   static void set_redirection(Redirection* r) { redirection_ = r; }
 
- private:
-  // Runtime call support. Uses the isolate in a thread-safe way.
-  static void* RedirectExternalReference(Isolate* isolate,
-                                         void* external_function,
-                                         ExternalReference::Type type);
-
-  static base::Mutex* redirection_mutex_;
-  static Redirection* redirection_;
-
+ protected:
   template <typename Return, typename SimT, typename CallImpl, typename... Args>
   static Return VariadicCall(SimT* sim, CallImpl call, byte* entry,
                              Args... args) {
@@ -51,6 +43,15 @@ class SimulatorBase {
     return ConvertReturn<Return>(ret);
   }
 
+ private:
+  // Runtime call support. Uses the isolate in a thread-safe way.
+  static void* RedirectExternalReference(Isolate* isolate,
+                                         void* external_function,
+                                         ExternalReference::Type type);
+
+  static base::Mutex* redirection_mutex_;
+  static Redirection* redirection_;
+
   // Helper methods to convert arbitrary integer or pointer arguments to the
   // needed generic argument type intptr_t.