AOT: Add a separate switchable call state for unlinked calls.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index c8bf048bb3de85b50f15d56e8087b2cac391cc1d..fbc72e2c24a5a105d437f65e793012dc5d5298a4 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -542,6 +542,7 @@ class Object {
   static RawClass* singletargetcache_class() {
     return singletargetcache_class_;
   }
+  static RawClass* unlinkedcall_class() { return unlinkedcall_class_; }
   static RawClass* icdata_class() { return icdata_class_; }
   static RawClass* megamorphic_cache_class() {
     return megamorphic_cache_class_;
@@ -794,6 +795,7 @@ class Object {
   static RawClass* context_class_;  // Class of the Context vm object.
   static RawClass* context_scope_class_;  // Class of ContextScope vm object.
   static RawClass* singletargetcache_class_;  // Class of SingleTargetCache.
+  static RawClass* unlinkedcall_class_;  // Class of UnlinkedCall.
   static RawClass* icdata_class_;  // Class of ICData.
   static RawClass* megamorphic_cache_class_;  // Class of MegamorphiCache.
   static RawClass* subtypetestcache_class_;  // Class of SubtypeTestCache.
@@ -1858,6 +1860,25 @@ DEFINE_NON_POINTER_FIELD_ACCESSORS(intptr_t, upper_limit);
 };
 
 
+class UnlinkedCall : public Object {
+ public:
+  RawString* target_name() const { return raw_ptr()->target_name_; }
+  void set_target_name(const String& target_name) const;
+  RawArray* args_descriptor() const { return raw_ptr()->args_descriptor_; }
+  void set_args_descriptor(const Array& args_descriptor) const;
+
+  static intptr_t InstanceSize() {
+    return RoundedAllocationSize(sizeof(RawUnlinkedCall));
+  }
+
+  static RawUnlinkedCall* New();
+
+ private:
+  FINAL_HEAP_OBJECT_IMPLEMENTATION(UnlinkedCall, Object);
+  friend class Class;
+};
+
+
 // Object holding information about an IC: test classes and their
 // corresponding targets. The owner of the ICData can be either the function
 // or the original ICData object. In case of background compilation we