Prepare for decoupling analyzer ASTs from element model.

pkg/analyzer/test/src/dart/constant/evaluation_test.dart

Index: pkg/analyzer/test/src/dart/constant/evaluation_test.dart
diff --git a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
index 43dfdf7b21dc033112b4f01fcaf68cdbfb1b69ce..e068d6e483da1ad5fcb220d78e0b2adcb174c750 100644
--- a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
+++ b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
@@ -6,6 +6,7 @@ library analyzer.test.constant_test;
 
 import 'package:analyzer/context/declared_variables.dart';
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/resolution_accessors.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
@@ -1589,7 +1590,7 @@ const b = 3;''');
 
   DartObjectImpl _evaluateConstant(CompilationUnit compilationUnit, String name,
       Map<String, DartObjectImpl> lexicalEnvironment) {
-    Source source = compilationUnit.element.source;
+    Source source = elementForCompilationUnit(compilationUnit).source;
     Expression expression =
         findTopLevelConstantExpression(compilationUnit, name);
     GatheringErrorListener errorListener = new GatheringErrorListener();