Optimize more megamorphic dispatch sites

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, 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 analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 596 matching lines @@
     for (FieldElement fieldElement in _fields) {
       if (name == fieldElement.name) {
         return fieldElement;
       }
     }
     return null;
   }
 
   @override
   PropertyAccessorElement getGetter(String getterName) {
-    for (PropertyAccessorElement accessor in _accessors) {
+    int length = _accessors.length;
+    for (int i = 0; i < length; i++) {
+      PropertyAccessorElement accessor = _accessors[i];
       if (accessor.isGetter && accessor.name == getterName) {
         return accessor;
       }
     }
     return null;
   }
 
   @override
   MethodElement getMethod(String methodName) {
-    for (MethodElement method in _methods) {
+    int length = _methods.length;
+    for (int i = 0; i < length; i++) {
+      MethodElement method = _methods[i];
       if (method.name == methodName) {
         return method;
       }
     }
     return null;
   }
 
   @override
   ConstructorElement getNamedConstructor(String name) {
     for (ConstructorElement element in constructors) {
@@ skipping 6252 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }