[Isolates] Merge crankshaft (r5922 from bleeding_edge).

src/vm-state.h

Index: src/vm-state.h
diff --git a/src/vm-state.h b/src/vm-state.h
index b7ecbf8e58b73be55df7f58db1f786a56f26231f..11fc6d67ef5981e0003ae52e6d52f2bbca41ed2a 100644
--- a/src/vm-state.h
+++ b/src/vm-state.h
@@ -36,39 +36,31 @@ namespace internal {
 class VMState BASE_EMBEDDED {
 #ifdef ENABLE_VMSTATE_TRACKING
  public:
-  inline VMState(Isolate* isolate, StateTag state);
+  inline VMState(Isolate* isolate, StateTag tag);
   inline ~VMState();
 
-  StateTag state() { return state_; }
-  void set_external_callback(Address external_callback) {
-    external_callback_ = external_callback;
-  }
-
-  // Used for debug asserts.
-  static bool is_outermost_external() {
-    return Isolate::Current()->current_vm_state() == 0;
-  }
+ private:
+  Isolate* isolate_;
+  StateTag previous_tag_;
 
-  static StateTag current_state() {
-    VMState* state = Isolate::Current()->current_vm_state();
-    return state ? state->state() : EXTERNAL;
-  }
+#else
+ public:
+  VMState(Isolate* isolate, StateTag state) {}
+#endif
+};
 
-  static Address external_callback() {
-    VMState* state = Isolate::Current()->current_vm_state();
-    return state ? state->external_callback_ : NULL;
-  }
 
+class ExternalCallbackScope BASE_EMBEDDED {
+#ifdef ENABLE_LOGGING_AND_PROFILING
+ public:
+  inline ExternalCallbackScope(Isolate* isolate, Address callback);
+  inline ~ExternalCallbackScope();
  private:
   Isolate* isolate_;
-  bool disabled_;
-  StateTag state_;
-  VMState* previous_;
-  Address external_callback_;
-
+  Address previous_callback_;
 #else
  public:
-  VMState(Isolate* isolate, StateTag state) {}
+  ExternalCallbackScope(Isolate* isolate, Address callback) {}
 #endif
 };