[turbofan] Properly handle dictionary maps in the prototype chain.

src/compilation-dependencies.cc

Index: src/compilation-dependencies.cc
diff --git a/src/compilation-dependencies.cc b/src/compilation-dependencies.cc
index 96b3859e9ab4b73eb22a7e41db3568ed59f30f52..183de2876ea957f531e01dcfe95599e0b78877ad 100644
--- a/src/compilation-dependencies.cc
+++ b/src/compilation-dependencies.cc
@@ -124,20 +124,6 @@ void CompilationDependencies::AssumeMapStable(Handle<Map> map) {
 }
 
 
-void CompilationDependencies::AssumePrototypeMapsStable(
-    Handle<Map> map, MaybeHandle<JSReceiver> prototype) {
-  for (PrototypeIterator i(map); !i.IsAtEnd(); i.Advance()) {
-    Handle<JSReceiver> const current =
-        PrototypeIterator::GetCurrent<JSReceiver>(i);
-    AssumeMapStable(handle(current->map()));
-    Handle<JSReceiver> last;
-    if (prototype.ToHandle(&last) && last.is_identical_to(current)) {
-      break;
-    }
-  }
-}
-
-
 void CompilationDependencies::AssumeTransitionStable(
     Handle<AllocationSite> site) {
   // Do nothing if the object doesn't have any useful element transitions left.