Use a WeakCell in the CallIC type vector.

test/cctest/test-compiler.cc

Index: test/cctest/test-compiler.cc
diff --git a/test/cctest/test-compiler.cc b/test/cctest/test-compiler.cc
index a05231e534833f911e3d8d468fd72750a45230d7..26ab3bf96d8c5b8d2b7719e33c9e141b35da8692 100644
--- a/test/cctest/test-compiler.cc
+++ b/test/cctest/test-compiler.cc
@@ -314,7 +314,9 @@ TEST(FeedbackVectorPreservedAcrossRecompiles) {
   CHECK_EQ(expected_slots, feedback_vector->Slots());
   CHECK_EQ(expected_ic_slots, feedback_vector->ICSlots());
   FeedbackVectorICSlot slot_for_a(0);
-  CHECK(feedback_vector->Get(slot_for_a)->IsJSFunction());
+  Object* object = feedback_vector->Get(slot_for_a);
+  CHECK(object->IsWeakCell() &&
+        WeakCell::cast(object)->value()->IsJSFunction());
 
   CompileRun("%OptimizeFunctionOnNextCall(f); f(fun1);");
 
@@ -322,7 +324,9 @@ TEST(FeedbackVectorPreservedAcrossRecompiles) {
   // of the full code.
   CHECK(f->IsOptimized());
   CHECK(f->shared()->has_deoptimization_support());
-  CHECK(f->shared()->feedback_vector()->Get(slot_for_a)->IsJSFunction());
+  object = f->shared()->feedback_vector()->Get(slot_for_a);
+  CHECK(object->IsWeakCell() &&
+        WeakCell::cast(object)->value()->IsJSFunction());
 }