Clean up VMState a little bit.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index 26833302aa9472b4718dcd5799c20c405470920b..8db13df805777776a84b3b4252b46a0847485577 100644
--- a/src/log.h
+++ b/src/log.h
@@ -163,7 +163,7 @@ class Logger {
 #undef DECLARE_ENUM
 
   // Acquires resources for logging if the right flags are set.
-  bool SetUp();
+  bool SetUp(Isolate* isolate);
 
   // Sets the current code event handler.
   void SetCodeEventHandler(uint32_t options,
@@ -292,8 +292,8 @@ class Logger {
 
   void TimerEvent(StartEnd se, const char* name);
 
-  static void EnterExternal();
-  static void LeaveExternal();
+  static void EnterExternal(Isolate* isolate);
+  static void LeaveExternal(Isolate* isolate);
 
   class TimerEventScope {
    public:
@@ -466,7 +466,7 @@ class Logger {
   friend class LogMessageBuilder;
   friend class TimeLog;
   friend class Profiler;
-  friend class VMState;
+  template <StateTag Tag> friend class VMState;
 
   friend class LoggerTestHelper;