[debugger] introduce abstract interface for break location.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index 2ddb90742e7e3bb85dd09329edf0e2cdeefbd6d5..7bd9ee65f2c98c7622e34df862d4d72f5d9bee95 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -618,13 +618,9 @@ class RelocInfo {
   template<typename StaticVisitor> inline void Visit(Heap* heap);
   inline void Visit(Isolate* isolate, ObjectVisitor* v);
 
-  // Check whether this return sequence has been patched
-  // with a call to the debugger.
-  INLINE(bool IsPatchedReturnSequence());
-
   // Check whether this debug break slot has been patched with a call to the
   // debugger.
-  INLINE(bool IsPatchedDebugBreakSlotSequence());
+  bool IsPatchedDebugBreakSlotSequence();
 
 #ifdef DEBUG
   // Check whether the given code contains relocation information that