Create and cache method extraction stub in the ICData.

runtime/vm/stub_code.h

Index: runtime/vm/stub_code.h
diff --git a/runtime/vm/stub_code.h b/runtime/vm/stub_code.h
index da0fe25b95bad8c67b125021f09e3fa74ada66ac..ee8dc54dd4452f5e4c065f4d52ed77991fce5553 100644
--- a/runtime/vm/stub_code.h
+++ b/runtime/vm/stub_code.h
@@ -156,6 +156,8 @@ class StubCode {
   static RawCode* GetAllocationStubForClass(const Class& cls);
   static RawCode* GetAllocationStubForClosure(const Function& func);
 
+  static RawFunction* GetMethodExtractor(const Function& closure_function);
+
   static const intptr_t kNoInstantiator = 0;
 
  private:
@@ -196,6 +198,8 @@ class StubCode {
   static void GenerateUsageCounterIncrement(Assembler* assembler,
                                             Register temp_reg);
   static void GenerateOptimizedUsageCounterIncrement(Assembler* assembler);
+  static void GenerateMethodExtractor(Assembler* assembler,
+                                      const Function& closure_function);
 };
 
 }  // namespace dart