Write barrier for storing a code entry, and usage in CompileLazy builtin.

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index 52d0ca4e51b6e297c04c94bfb686116722d32bba..a0243aa9cc92a03e8bf05ba12fca807cf38639e9 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -91,6 +91,18 @@ void IncrementalMarking::RecordWriteFromCode(HeapObject* obj, Object** slot,
   marking->RecordWrite(obj, slot, *slot);
 }
 
+// static
+void IncrementalMarking::RecordWriteOfCodeEntryFromCode(JSFunction* host,
+                                                        Object** slot,
+                                                        Isolate* isolate) {
+  DCHECK(host->IsJSFunction());
+  IncrementalMarking* marking = isolate->heap()->incremental_marking();
+  Code* value = Code::cast(
+      Code::GetObjectFromEntryAddress(reinterpret_cast<Address>(slot)));
+  // TODO(mvstanton): Verify that we only come in here when we _need_ to be
+  // here, the slow case should be dealt with before calling into C.
+  marking->RecordWriteOfCodeEntry(host, slot, value);
+}
 
 void IncrementalMarking::RecordCodeTargetPatch(Code* host, Address pc,
                                                HeapObject* value) {