Refactor dependent code.

src/crankshaft/lithium.cc

Index: src/crankshaft/lithium.cc
diff --git a/src/crankshaft/lithium.cc b/src/crankshaft/lithium.cc
index b4771c055708bf3e409cc2aaa0d9cfbb4d20ddd1..ab3d53ee9a1c057c1ac95c74230896cc984f9312 100644
--- a/src/crankshaft/lithium.cc
+++ b/src/crankshaft/lithium.cc
@@ -441,8 +441,7 @@ void LChunk::RegisterWeakObjectsInOptimizedCode(Handle<Code> code) const {
     }
   }
   for (int i = 0; i < maps.length(); i++) {
-    if (maps.at(i)->dependent_code()->number_of_entries(
-            DependentCode::kWeakCodeGroup) == 0) {
+    if (maps.at(i)->dependent_code()->IsEmpty(DependentCode::kWeakCodeGroup)) {
       isolate()->heap()->AddRetainedMap(maps.at(i));
     }
     Map::AddDependentCode(maps.at(i), DependentCode::kWeakCodeGroup, code);