Add a HBreak instruction for debugging

src/mips/lithium-mips.h

Index: src/mips/lithium-mips.h
diff --git a/src/mips/lithium-mips.h b/src/mips/lithium-mips.h
index 4f8eecdb472c224d47738c2def2df0bcfd5fefaf..4f48aecae7c77e0af80caee40f0eeb84c501fdcb 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -60,6 +60,7 @@ class LCodeGen;
   V(BitNotI)                                    \
   V(BoundsCheck)                                \
   V(Branch)                                     \
+  V(Break)                                      \
   V(CallConstantFunction)                       \
   V(CallFunction)                               \
   V(CallGlobal)                                 \
@@ -655,6 +656,12 @@ class LMultiplyAddD: public LTemplateInstruction<1, 3, 0> {
 };
 
 
+class LBreak: public LTemplateInstruction<0, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(Break, "break")
+};
+
+
 class LCmpIDAndBranch: public LControlInstruction<2, 0> {
  public:
   LCmpIDAndBranch(LOperand* left, LOperand* right) {