Revert of [debugger api] remove legacy JSON debug protocol.

src/execution.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_EXECUTION_H_
 #define V8_EXECUTION_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/handles.h"
@@ skipping 68 matching lines @@
   void FreeThreadResources();
   // Sets up the default stack guard for this thread if it has not
   // already been set up.
   void InitThread(const ExecutionAccess& lock);
   // Clears the stack guard for this thread so it does not look as if
   // it has been set up.
   void ClearThread(const ExecutionAccess& lock);
 
 #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)
+  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 V(NAME, Name, id)                                          \
   inline bool Check##Name() { return CheckInterrupt(NAME); }  \
   inline void Request##Name() { RequestInterrupt(NAME); }     \
   inline void Clear##Name() { ClearInterrupt(NAME); }
   INTERRUPT_LIST(V)
 #undef V
 
   // Flag used to set the interrupt causes.
   enum InterruptFlag {
@@ skipping 118 matching lines @@
   friend class StackLimitCheck;
   friend class PostponeInterruptsScope;
 
   DISALLOW_COPY_AND_ASSIGN(StackGuard);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_EXECUTION_H_