Create and cache method extraction stub in the ICData.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index d59cd8264f749f1158f690b0a983ce27145034f3..17fe0c36f15ab9b5fb046c1caeb6434267ccefac 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1156,6 +1156,16 @@ class Function : public Object {
   RawCode* closure_allocation_stub() const;
   void set_closure_allocation_stub(const Code& value) const;
 
+  RawFunction* method_extractor() const;
+  void set_method_extractor(const Function& value) const;
+
+  void set_extracted_method_closure(const Function& function) const;
+  RawFunction* extracted_method_closure() const;
+
+  bool IsMethodExtractor() const {
+    return kind() == RawFunction::kMethodExtractor;
+  }
+
   // Returns true iff an implicit closure function has been created
   // for this function.
   bool HasImplicitClosureFunction() const {
@@ -1572,6 +1582,11 @@ class ClosureData: public Object {
   }
   void set_closure_allocation_stub(const Code& value) const;
 
+  RawFunction* method_extractor() const {
+    return raw_ptr()->method_extractor_;
+  }
+  void set_method_extractor(const Function& value) const;
+
   static RawClosureData* New();
 
   HEAP_OBJECT_IMPLEMENTATION(ClosureData, Object);