Test that profiler is stopped when isolate is being disposed

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index cf01684729d9f4a433fbd1008d728752de6919a5..c9ad81f50150d3ccc8b62e31efd36bc35c524079 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -3993,8 +3993,9 @@ class V8EXPORT Isolate {
   HeapProfiler* GetHeapProfiler();
 
   /**
-   * Returns CPU profiler for this isolate. Will return NULL until the isolate
-   * is initialized.
+   * Returns CPU profiler for this isolate. Will return NULL unless the isolate
+   * is initialized. It is the embedder's responsibility to stop all CPU
+   * profiling activities if it has started any.
    */
   CpuProfiler* GetCpuProfiler();