Get rid of obsolete unchecked accessors.

src/compilation-cache.cc

Index: src/compilation-cache.cc
diff --git a/src/compilation-cache.cc b/src/compilation-cache.cc
index c0645760b3f8655ff711944902e7809b57cd0811..904e84fd6cfe9c03889761df01d1bb978c4db6bb 100644
--- a/src/compilation-cache.cc
+++ b/src/compilation-cache.cc
@@ -98,7 +98,7 @@ void CompilationSubCache::Age() {
 
 
 void CompilationSubCache::IterateFunctions(ObjectVisitor* v) {
-  Object* undefined = isolate()->heap()->raw_unchecked_undefined_value();
+  Object* undefined = isolate()->heap()->undefined_value();
   for (int i = 0; i < generations_; i++) {
     if (tables_[i] != undefined) {
       reinterpret_cast<CompilationCacheTable*>(tables_[i])->IterateElements(v);