Implement IC support for Constant Function transitions.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index c1059050ce16799d123f6d9dfececc37b58baade..dce2a7e2e8dba1759c2b354e5a0cb6aed9288252 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -817,7 +817,13 @@ void StubCompiler::GenerateStoreTransition(MacroAssembler* masm,
 
   Register storage_reg = name_reg;
 
-  if (FLAG_track_fields && representation.IsSmi()) {
+  if (details.type() == CONSTANT_FUNCTION) {
+    Handle<HeapObject> constant(
+        HeapObject::cast(descriptors->GetValue(descriptor)));
+    __ LoadHeapObject(scratch1, constant);
+    __ cmpq(value_reg, scratch1);
+    __ j(not_equal, miss_restore_name);
+  } else if (FLAG_track_fields && representation.IsSmi()) {
     __ JumpIfNotSmi(value_reg, miss_restore_name);
   } else if (FLAG_track_heap_object_fields && representation.IsHeapObject()) {
     __ JumpIfSmi(value_reg, miss_restore_name);
@@ -873,6 +879,8 @@ void StubCompiler::GenerateStoreTransition(MacroAssembler* masm,
                       OMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
 
+  if (details.type() == CONSTANT_FUNCTION) return;
+
   int index = transition->instance_descriptors()->GetFieldIndex(
       transition->LastAdded());