Abstract out fetching of break_address in debug mode

src/x87/assembler-x87.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 504 matching lines @@
   // and the return address
   static const int kCallTargetAddressOffset = kPointerSize;
   // Distance between start of patched return sequence and the emitted address
   // to jump to.
   static const int kPatchReturnSequenceAddressOffset = 1;  // JMP imm32.
 
   // Distance between start of patched debug break slot and the emitted address
   // to jump to.
   static const int kPatchDebugBreakSlotAddressOffset = 1;  // JMP imm32.
 
+  // Return the code target address of the patch debug break slot
+  inline static Address break_address_from_break_address(Address pc);
+
   static const int kCallInstructionLength = 5;
   static const int kPatchDebugBreakSlotReturnOffset = kPointerSize;
   static const int kJSReturnSequenceLength = 6;
 
   // The debug break slot must be able to contain a call instruction.
   static const int kDebugBreakSlotLength = kCallInstructionLength;
 
   // One byte opcode for test al, 0xXX.
   static const byte kTestAlByte = 0xA8;
   // One byte opcode for nop.
@@ skipping 487 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X87_ASSEMBLER_X87_H_