Add a HBreak instruction for debugging

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 9deed587e3fb9b7bf51f252fb2effbbd0bf78a5c..2f6d223886a1b1ee08c11a8bd425accf1644b164 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -60,6 +60,7 @@ class LCodeGen;
   V(BitNotI)                                    \
   V(BoundsCheck)                                \
   V(Branch)                                     \
+  V(Break)                                      \
   V(CallConstantFunction)                       \
   V(CallFunction)                               \
   V(CallGlobal)                                 \
@@ -695,6 +696,12 @@ class LMultiplySubD: 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) {