Retaining path improvements.

runtime/vm/object_graph.cc

Index: runtime/vm/object_graph.cc
diff --git a/runtime/vm/object_graph.cc b/runtime/vm/object_graph.cc
index 879e87ca07c1702aa69f9382b19ffeaef951b606..ad6f8614821e9e866f971ef954992724c482045a 100644
--- a/runtime/vm/object_graph.cc
+++ b/runtime/vm/object_graph.cc
@@ -261,9 +261,25 @@ class RetainingPathVisitor : public ObjectGraph::Visitor {
 
   intptr_t length() const { return length_; }
 
+  bool ShouldSkip(RawObject* obj) {
+    // A retaining path through ICData is never the only retaining path,
+    // and it is less informative than its alternatives.
+    intptr_t cid = obj->GetClassId();
+    switch (cid) {
+    case kICDataCid:
+      return true;
+    default:
+      return false;
+    }
+  }
+
   virtual Direction VisitObject(ObjectGraph::StackIterator* it) {
     if (it->Get() != obj_) {
-      return kProceed;
+      if (ShouldSkip(it->Get())) {
+        return kBacktrack;
+      } else {
+        return kProceed;
+      }
     } else {
       HANDLESCOPE(Isolate::Current());
       Object& current = Object::Handle();