Added tests; improved test output; code clean-up

pkg/analyzer/lib/src/generated/constant.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.generated.constant;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 1303 matching lines @@
   Object visitVariableDeclaration(VariableDeclaration node) {
     super.visitVariableDeclaration(node);
     Expression initializer = node.initializer;
     VariableElement element = node.element;
     if (initializer != null &&
         (node.isConst ||
             treatFinalInstanceVarAsConst &&
                 element is FieldElement &&
                 node.isFinal &&
                 !element.isStatic)) {
-      if (node.element != null) {
-        constantsToCompute.add(node.element);
+      if (element != null) {
+        constantsToCompute.add(element);
       }
     }
     return null;
   }
 }
 
 /**
  * An object used to compute the values of constant variables and constant
  * constructor invocations in one or more compilation units. The expected usage
  * pattern is for the compilation units to be added to this computer using the
@@ skipping 4077 matching lines @@
       return BoolState.from(_element == rightElement);
     } else if (rightOperand is DynamicState) {
       return BoolState.UNKNOWN_VALUE;
     }
     return BoolState.FALSE_STATE;
   }
 
   @override
   String toString() => _element == null ? "-unknown-" : _element.name;
 }