Make the Isolate parameter mandatory in Locker and Unlocker classes.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 8d0575c52d7909063209ed24b37692954092200a..d43c451e97c0e1645397b7005511b889a613fdbd 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1070,6 +1070,11 @@ class Isolate {
     return &optimizing_compiler_thread_;
   }
 
+  // PreInits and returns a default isolate. Needed when a new thread tries
+  // to create a Locker for the first time (the lock itself is in the isolate).
+  // TODO(svenpanne) This method is on death row...
+  static v8::Isolate* GetDefaultIsolateForLocking();
+
  private:
   Isolate();
 
@@ -1153,10 +1158,6 @@ class Isolate {
   // If one does not yet exist, allocate a new one.
   PerIsolateThreadData* FindOrAllocatePerThreadDataForThisThread();
 
-  // PreInits and returns a default isolate. Needed when a new thread tries
-  // to create a Locker for the first time (the lock itself is in the isolate).
-  static Isolate* GetDefaultIsolateForLocking();
-
   // Initializes the current thread to run this Isolate.
   // Not thread-safe. Multiple threads should not Enter/Exit the same isolate
   // at the same time, this should be prevented using external locking.