[debugger] introduce abstract interface for break location.

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index b183c9c8e030b29ca734943e89281dd5430d3a65..fafa80d7e03199a4138cb79752a0e948ddaa58a7 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -1021,7 +1021,7 @@ void NormalizedMapCache::NormalizedMapCacheVerify() {
 void DebugInfo::DebugInfoVerify() {
   CHECK(IsDebugInfo());
   VerifyPointer(shared());
-  VerifyPointer(code());
+  VerifyPointer(abstract_code());
   VerifyPointer(break_points());
 }