[debugger] deprecate v8::Debug:GetDebugContext.

include/v8-debug.h

Index: include/v8-debug.h
diff --git a/include/v8-debug.h b/include/v8-debug.h
index 948972e9b5ecdddc52ecdea9c9297e9af57521df..777b8aaa3e645a1c6024d46ebab5bbc70754cd1b 100644
--- a/include/v8-debug.h
+++ b/include/v8-debug.h
@@ -248,7 +248,8 @@ class V8_EXPORT Debug {
    * to change. The Context exists only when the debugger is active, i.e. at
    * least one DebugEventListener or MessageHandler is set.
    */
-  static Local<Context> GetDebugContext(Isolate* isolate);
+  V8_DEPRECATED("Use v8-inspector",
+                static Local<Context> GetDebugContext(Isolate* isolate));
 
   /**
    * While in the debug context, this method returns the top-most non-debug