Reduce use of Element in optimize.dart

pkg/compiler/lib/src/world.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.world;
 
 import 'closure.dart' show ClosureClassElement, SynthesizedCallMethodElementX;
 import 'common/backend_api.dart' show BackendClasses;
 import 'common.dart';
 import 'constants/constant_system.dart';
@@ skipping 234 matching lines @@
   /// Return the cached mask for [base] with the given flags, or
   /// calls [createMask] to create the mask and cache it.
   // TODO(johnniwinther): Find a better strategy for caching these?
   TypeMask getCachedMask(ClassElement base, int flags, TypeMask createMask());
 
   /// Returns the [FunctionSet] containing all live functions in the closed
   /// world.
   FunctionSet get allFunctions;
 
   /// Returns `true` if the field [element] is known to be effectively final.
-  bool fieldNeverChanges(Element element);
+  bool fieldNeverChanges(MemberElement element);
 
   /// Extends the receiver type [mask] for calling [selector] to take live
   /// `noSuchMethod` handlers into account.
   TypeMask extendMaskIfReachesAll(Selector selector, TypeMask mask);
 
   /// Returns all resolved typedefs.
   Iterable<TypedefElement> get allTypedefs;
 
   /// Returns the single [Element] that matches a call to [selector] on a
   /// receiver of type [mask]. If multiple targets exist, `null` is returned.
-  Element locateSingleElement(Selector selector, TypeMask mask);
+  MemberElement locateSingleElement(Selector selector, TypeMask mask);
 
   /// Returns the single field that matches a call to [selector] on a
   /// receiver of type [mask]. If multiple targets exist or the single target
   /// is not a field, `null` is returned.
   FieldElement locateSingleField(Selector selector, TypeMask mask);
 
   /// Returns the side effects of executing [element].
   SideEffects getSideEffectsOfElement(Element element);
 
   /// Returns the side effects of calling [selector] on a receiver of type
@@ skipping 729 matching lines @@
   }
 
   void addFunctionCalledInLoop(Element element) {
     functionsCalledInLoop.add(element.declaration);
   }
 
   bool isCalledInLoop(Element element) {
     return functionsCalledInLoop.contains(element.declaration);
   }
 
-  bool fieldNeverChanges(Element element) {
+  bool fieldNeverChanges(MemberElement element) {
     if (!element.isField) return false;
     if (_backend.isNative(element)) {
       // Some native fields are views of data that may be changed by operations.
       // E.g. node.firstChild depends on parentNode.removeBefore(n1, n2).
       // TODO(sra): Refine the effect classification so that native effects are
       // distinct from ordinary Dart effects.
       return false;
     }
 
     if (element.isFinal || element.isConst) {
@@ skipping 82 matching lines @@
       return getMightBePassedToApply(element.expression);
     }
     return functionsThatMightBePassedToApply.contains(element);
   }
 
   @override
   bool getCurrentlyKnownMightBePassedToApply(Element element) {
     return getMightBePassedToApply(element);
   }
 }