Reduce usage of .enclosingElement to get enclosing class.

lib/compiler/implementation/compile_time_constants.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.
 
 class Constant implements Hashable {
   const Constant();
 
   bool isNull() => false;
   bool isBool() => false;
   bool isTrue() => false;
@@ skipping 969 matching lines @@
                                                  compiler);
     assert(succeeded);
     return compiledArguments;
   }
 
   Constant visitNewExpression(NewExpression node) {
     if (!node.isConst()) error(node);
 
     Send send = node.send;
     FunctionElement constructor = elements[send];
-    ClassElement classElement = constructor.enclosingElement;
+    ClassElement classElement = constructor.getEnclosingClass();
     if (classElement.isInterface()) {
       compiler.resolver.resolveMethodElement(constructor);
       constructor = constructor.defaultImplementation;
-      classElement = constructor.enclosingElement;
+      classElement = constructor.getEnclosingClass();
     }
 
     Selector selector = elements.getSelector(send);
     List<Constant> arguments =
         evaluateArgumentsToConstructor(selector, send.arguments, constructor);
     ConstructorEvaluator evaluator =
         new ConstructorEvaluator(constructor, compiler);
     evaluator.evaluateConstructorFieldValues(arguments);
     List<Constant> jsNewArguments = evaluator.buildJsNewArguments(classElement);
 
@@ skipping 114 matching lines @@
           assert(!initArguments.isEmpty() && initArguments.tail.isEmpty());
           Constant fieldValue = evaluate(initArguments.head);
           fieldValues[elements[init]] = fieldValue;
         }
       }
     }
 
     if (!foundSuperOrRedirect) {
       // No super initializer found. Try to find the default constructor if
       // the class is not Object.
-      ClassElement enclosingClass = constructor.enclosingElement;
+      ClassElement enclosingClass = constructor.getEnclosingClass();
       ClassElement superClass = enclosingClass.superclass;
       if (enclosingClass != compiler.objectClass) {
         assert(superClass !== null);
         assert(superClass.isResolved);
         FunctionElement targetConstructor =
             superClass.lookupConstructor(superClass.name);
         if (targetConstructor === null) {
           compiler.internalError("no default constructor available",
                                  node: functionNode);
         }
@@ skipping 26 matching lines @@
       Constant fieldValue = fieldValues[field];
       if (fieldValue === null) {
         // Use the default value.
         fieldValue = compiler.compileVariable(field);
       }
       jsNewArguments.add(fieldValue);
     });
     return jsNewArguments;
   }
 }