Add a HBreak instruction for debugging

src/ia32/lithium-codegen-ia32.cc

 // 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 3481 matching lines @@
   LPointerMap* pointers = instr->pointer_map();
   RecordPosition(pointers->position());
   SafepointGenerator safepoint_generator(
       this, pointers, Safepoint::kLazyDeopt);
   ParameterCount actual(eax);
   __ InvokeFunction(function, actual, CALL_FUNCTION,
                     safepoint_generator, CALL_AS_METHOD);
 }
 
 
+void LCodeGen::DoBreak(LBreak* instr) {
+  __ int3();
+}
+
+
 void LCodeGen::DoPushArgument(LPushArgument* instr) {
   LOperand* argument = instr->value();
   EmitPushTaggedOperand(argument);
 }
 
 
 void LCodeGen::DoDrop(LDrop* instr) {
   __ Drop(instr->count());
 }
 
@@ skipping 2993 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32