Fix bug 542, misleading documentation of v8::Locker.

include/v8.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2699 matching lines @@
 
 class RetainedObjectInfo;
 
 /**
  * Isolate represents an isolated instance of the V8 engine.  V8
  * isolates have completely separate states.  Objects from one isolate
  * must not be used in other isolates.  When V8 is initialized a
  * default isolate is implicitly created and entered.  The embedder
  * can create additional isolates and use them in parallel in multiple
  * threads.  An isolate can be entered by at most one thread at any
- * given time.  The Locker/Unlocker API can be used to synchronize.
+ * given time.  The Locker/Unlocker API must be used to synchronize.
  */
 class V8EXPORT Isolate {
  public:
   /**
    * Stack-allocated class which sets the isolate for all operations
    * executed within a local scope.
    */
   class V8EXPORT Scope {
    public:
     explicit Scope(Isolate* isolate) : isolate_(isolate) {
@@ skipping 821 matching lines @@
 };
 
 
 /**
  * Multiple threads in V8 are allowed, but only one thread at a time
  * is allowed to use any given V8 isolate. See Isolate class
  * comments. The definition of 'using V8 isolate' includes
  * accessing handles or holding onto object pointers obtained
  * from V8 handles while in the particular V8 isolate.  It is up
  * to the user of V8 to ensure (perhaps with locking) that this
- * constraint is not violated.
+ * constraint is not violated.  In addition to any other synchronization
+ * mechanism that may be used, the v8::Locker and v8::Unlocker classes
+ * must be used to signal thead switches to V8.
  *
  * v8::Locker is a scoped lock object. While it's
  * active (i.e. between its construction and destruction) the current thread is
  * allowed to use the locked isolate. V8 guarantees that an isolate can be
  * locked by at most one thread at any time. In other words, the scope of a
  * v8::Locker is a critical section.
  *
  * Sample usage:
 * \code
  * ...
@@ skipping 693 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_