[debugger] add precise mode for code coverage.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index d8986f3557394fe8cd4ef69867641f5b167c8710..621e41ae7ff7ead94edfa5b903b042a8c027dbf7 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -208,6 +208,8 @@ using v8::MemoryPressureLevel;
   /* slots refer to the code with the reference to the weak object. */         \
   V(ArrayList, weak_new_space_object_to_code_list,                             \
     WeakNewSpaceObjectToCodeList)                                              \
+  /* List to hold onto feedback vectors that we need for code coverage */      \
+  V(Object, code_coverage_list, CodeCoverageList)                              \
   V(Object, weak_stack_trace_list, WeakStackTraceList)                         \
   V(Object, noscript_shared_function_infos, NoScriptSharedFunctionInfos)       \
   V(FixedArray, serialized_templates, SerializedTemplates)                     \