Add debugger protocol request for setting global flags.

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index fb9269272f1f2200b00cd9a20c5eba0d2e9f1a40..fe52efa1af44a9947ee65bca6e38dfc9353651c3 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -887,8 +887,6 @@ class EnterDebugger BASE_EMBEDDED {
 // Stack allocated class for disabling break.
 class DisableBreak BASE_EMBEDDED {
  public:
-  // Enter the debugger by storing the previous top context and setting the
-  // current top context to the debugger context.
   explicit DisableBreak(bool disable_break)  {
     prev_disable_break_ = Debug::disable_break();
     Debug::set_disable_break(disable_break);