Abstract out fetching of break_address in debug mode

src/ia32/assembler-ia32-inl.h

Index: src/ia32/assembler-ia32-inl.h
diff --git a/src/ia32/assembler-ia32-inl.h b/src/ia32/assembler-ia32-inl.h
index ff8978c966b2274ee0883742d5dabdf803356f07..d6070883c8384c1f0c4b190e89ef7c0456366139 100644
--- a/src/ia32/assembler-ia32-inl.h
+++ b/src/ia32/assembler-ia32-inl.h
@@ -482,6 +482,11 @@ Address Assembler::target_address_from_return_address(Address pc) {
 }
 
 
+Address Assembler::break_address_from_return_address(Address pc) {
+  return pc - Assembler::kPatchDebugBreakSlotReturnOffset;
+}
+
+
 Displacement Assembler::disp_at(Label* L) {
   return Displacement(long_at(L->pos()));
 }