[debug] remove deprecated debug command message queue.

src/execution.h

Index: src/execution.h
diff --git a/src/execution.h b/src/execution.h
index 6f4bb331a329aaf0c8c85ccbf09093d904070dda..b6988a19fe43b9ed3486f2c2863c4e56ea3f1cd5 100644
--- a/src/execution.h
+++ b/src/execution.h
@@ -79,14 +79,13 @@ class StackGuard final {
   // it has been set up.
   void ClearThread(const ExecutionAccess& lock);
 
-#define INTERRUPT_LIST(V)                                          \
-  V(DEBUGBREAK, DebugBreak, 0)                                     \
-  V(DEBUGCOMMAND, DebugCommand, 1)                                 \
-  V(TERMINATE_EXECUTION, TerminateExecution, 2)                    \
-  V(GC_REQUEST, GC, 3)                                             \
-  V(INSTALL_CODE, InstallCode, 4)                                  \
-  V(API_INTERRUPT, ApiInterrupt, 5)                                \
-  V(DEOPT_MARKED_ALLOCATION_SITES, DeoptMarkedAllocationSites, 6)
+#define INTERRUPT_LIST(V)                       \
+  V(DEBUGBREAK, DebugBreak, 0)                  \
+  V(TERMINATE_EXECUTION, TerminateExecution, 1) \
+  V(GC_REQUEST, GC, 2)                          \
+  V(INSTALL_CODE, InstallCode, 3)               \
+  V(API_INTERRUPT, ApiInterrupt, 4)             \
+  V(DEOPT_MARKED_ALLOCATION_SITES, DeoptMarkedAllocationSites, 5)
 
 #define V(NAME, Name, id)                                          \
   inline bool Check##Name() { return CheckInterrupt(NAME); }  \