Add a HBreak instruction for debugging

src/x64/lithium-x64.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 42 matching lines @@
   V(AllocateObject)                             \
   V(ApplyArguments)                             \
   V(ArgumentsElements)                          \
   V(ArgumentsLength)                            \
   V(ArithmeticD)                                \
   V(ArithmeticT)                                \
   V(BitI)                                       \
   V(BitNotI)                                    \
   V(BoundsCheck)                                \
   V(Branch)                                     \
+  V(Break)                                      \
   V(CallConstantFunction)                       \
   V(CallFunction)                               \
   V(CallGlobal)                                 \
   V(CallKeyed)                                  \
   V(CallKnownGlobal)                            \
   V(CallNamed)                                  \
   V(CallNew)                                    \
   V(CallNewArray)                               \
   V(CallRuntime)                                \
   V(CallStub)                                   \
@@ skipping 1092 matching lines @@
 
   LOperand* value() { return inputs_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(Branch, "branch")
   DECLARE_HYDROGEN_ACCESSOR(Branch)
 
   virtual void PrintDataTo(StringStream* stream);
 };
 
 
+class LBreak: public LTemplateInstruction<0, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(Break, "break")
+};
+
+
 class LCmpMapAndBranch: public LTemplateInstruction<0, 1, 0> {
  public:
   explicit LCmpMapAndBranch(LOperand* value) {
     inputs_[0] = value;
   }
 
   LOperand* value() { return inputs_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(CmpMapAndBranch, "cmp-map-and-branch")
   DECLARE_HYDROGEN_ACCESSOR(CompareMap)
@@ skipping 1522 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_