Revert "Inobject slack tracking is done on a per-closure basis instead of per-shared info basis."

src/heap-snapshot-generator.cc

Index: src/heap-snapshot-generator.cc
diff --git a/src/heap-snapshot-generator.cc b/src/heap-snapshot-generator.cc
index e6c80fa25ee4439a36f7a78225c7d2c74467460a..87d7819da5be0af475e9b68b6f5a033570cb1ae9 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -1421,6 +1421,9 @@ void V8HeapExplorer::ExtractSharedFunctionInfoReferences(
   SetInternalReference(obj, entry,
                        "feedback_vector", shared->feedback_vector(),
                        SharedFunctionInfo::kFeedbackVectorOffset);
+  SetWeakReference(obj, entry,
+                   "initial_map", shared->initial_map(),
+                   SharedFunctionInfo::kInitialMapOffset);
 }