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..1abea90141b67dc2ab1e22ba01832d0f1117496a 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -89,6 +89,7 @@ class LCodeGen;
   V(ConstantI)                                  \
   V(ConstantT)                                  \
   V(Context)                                    \
+  V(DebugBreak)                                 \
   V(DeclareGlobals)                             \
   V(DeleteProperty)                             \
   V(Deoptimize)                                 \
@@ -655,6 +656,12 @@ class LMultiplyAddD: public LTemplateInstruction<1, 3, 0> {
 };
 
 
+class LDebugBreak: public LTemplateInstruction<0, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(DebugBreak, "break")
+};
+
+
 class LCmpIDAndBranch: public LControlInstruction<2, 0> {
  public:
   LCmpIDAndBranch(LOperand* left, LOperand* right) {