Move ListImplementation from coreimpl to core, as a private member.

runtime/vm/intrinsifier_x64.cc

Index: runtime/vm/intrinsifier_x64.cc
diff --git a/runtime/vm/intrinsifier_x64.cc b/runtime/vm/intrinsifier_x64.cc
index affbf673bcfb51bd8317e3148646ede9a3c5dc14..5f3f96d8e5b114a0b0cf5ff58e4b5a6e36ffdc75 100644
--- a/runtime/vm/intrinsifier_x64.cc
+++ b/runtime/vm/intrinsifier_x64.cc
@@ -1409,9 +1409,9 @@ static intptr_t GetOffsetForField(const char* class_name_p,
                                   const char* field_name_p) {
   const String& class_name = String::Handle(Symbols::New(class_name_p));
   const String& field_name = String::Handle(Symbols::New(field_name_p));
-  const Library& coreimpl_lib = Library::Handle(Library::CoreImplLibrary());
+  const Library& core_lib = Library::Handle(Library::CoreLibrary());
   const Class& cls =
-      Class::Handle(coreimpl_lib.LookupClassAllowPrivate(class_name));
+      Class::Handle(core_lib.LookupClassAllowPrivate(class_name));
   ASSERT(!cls.IsNull());
   const Field& field = Field::ZoneHandle(cls.LookupInstanceField(field_name));
   ASSERT(!field.IsNull());