Optimize getField by caching a closure generated from a specialized function kind.

runtime/vm/parser.h

Index: runtime/vm/parser.h
diff --git a/runtime/vm/parser.h b/runtime/vm/parser.h
index 321a56f5b6998c8a904f0fe42d557ad9914e9431..aebbfb64bfdee7062ee11700b04fe88e5602d30d 100644
--- a/runtime/vm/parser.h
+++ b/runtime/vm/parser.h
@@ -445,6 +445,8 @@ class Parser : public ValueObject {
 
   SequenceNode* ParseInstanceGetter(const Function& func);
   SequenceNode* ParseInstanceSetter(const Function& func);
+  SequenceNode* ParseGetFieldClosure(const Function& func);
+  SequenceNode* ParseSetFieldClosure(const Function& func);
   SequenceNode* ParseStaticFinalGetter(const Function& func);
   SequenceNode* ParseStaticInitializer(const Function& func);
   SequenceNode* ParseMethodExtractor(const Function& func);