[turbofan] Initial support for monomorphic/polymorphic property loads.

src/compilation-dependencies.h

Index: src/compilation-dependencies.h
diff --git a/src/compilation-dependencies.h b/src/compilation-dependencies.h
index e7ee58fffc26d6aeb7017506150ebf6e83b1703b..93c1bb8247a841300029b1373cf67568719d8048 100644
--- a/src/compilation-dependencies.h
+++ b/src/compilation-dependencies.h
@@ -31,6 +31,7 @@ class CompilationDependencies {
   void AssumeFieldType(Handle<Map> map) {
     Insert(DependentCode::kFieldTypeGroup, map);
   }
+  void AssumeMapStable(Handle<Map> map);
   void AssumePropertyCell(Handle<PropertyCell> cell) {
     Insert(DependentCode::kPropertyCellChangedGroup, cell);
   }