Make embedded maps in optimized code weak.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 4cc47d0405a2dac3fad5b79c8fe9a692b46751af..1594ded7d32a3a6f8e5c59cea77bf3528ee7ca70 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -2168,6 +2168,7 @@ MaybeObject* Heap::AllocateMap(InstanceType instance_type,
   map->set_inobject_properties(0);
   map->set_pre_allocated_property_fields(0);
   map->set_code_cache(empty_fixed_array(), SKIP_WRITE_BARRIER);
+  map->set_dependent_codes(empty_fixed_array(), SKIP_WRITE_BARRIER);
   map->init_back_pointer(undefined_value());
   map->set_unused_property_fields(0);
   map->set_instance_descriptors(empty_descriptor_array());
@@ -2303,14 +2304,17 @@ bool Heap::CreateInitialMaps() {
 
   // Fix the instance_descriptors for the existing maps.
   meta_map()->set_code_cache(empty_fixed_array());
+  meta_map()->set_dependent_codes(empty_fixed_array());
   meta_map()->init_back_pointer(undefined_value());
   meta_map()->set_instance_descriptors(empty_descriptor_array());
 
   fixed_array_map()->set_code_cache(empty_fixed_array());
+  fixed_array_map()->set_dependent_codes(empty_fixed_array());
   fixed_array_map()->init_back_pointer(undefined_value());
   fixed_array_map()->set_instance_descriptors(empty_descriptor_array());
 
   oddball_map()->set_code_cache(empty_fixed_array());
+  oddball_map()->set_dependent_codes(empty_fixed_array());
   oddball_map()->init_back_pointer(undefined_value());
   oddball_map()->set_instance_descriptors(empty_descriptor_array());
 
@@ -3757,6 +3761,9 @@ MaybeObject* Heap::CreateCode(const CodeDesc& desc,
   code->set_gc_metadata(Smi::FromInt(0));
   code->set_ic_age(global_ic_age_);
   code->set_prologue_offset(kPrologueOffsetNotSet);
+  if (code->kind() == Code::OPTIMIZED_FUNCTION) {
+    code->set_marked_for_deoptimization(false);
+  }
   // Allow self references to created code object by patching the handle to
   // point to the newly allocated Code object.
   if (!self_reference.is_null()) {