Prepare for decoupling analyzer ASTs from element model.

pkg/analyzer/test/src/task/strong/strong_test_helper.dart

Index: pkg/analyzer/test/src/task/strong/strong_test_helper.dart
diff --git a/pkg/analyzer/test/src/task/strong/strong_test_helper.dart b/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
index 2b8314d19e63d7ed738cf82dd68f78fca33518ae..4d1f8576d8a95cca0d73b7c5a440bf74121e74b1 100644
--- a/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
+++ b/pkg/analyzer/test/src/task/strong/strong_test_helper.dart
@@ -7,6 +7,7 @@
 library analyzer.test.src.task.strong.strong_test_helper;
 
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/standard_resolution_map.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
@@ -87,7 +88,8 @@ CompilationUnit check(
 
   // Extract expectations from the comments in the test files, and
   // check that all errors we emit are included in the expected map.
-  var allLibraries = _reachableLibraries(initialLibrary.element.library);
+  var allLibraries = _reachableLibraries(
+      resolutionMap.elementForCompilationUnit(initialLibrary).library);
   for (var lib in allLibraries) {
     for (var unit in lib.units) {
       var errors = <AnalysisError>[];
@@ -283,13 +285,14 @@ void _reportFailure(
     Map<_ErrorExpectation, AnalysisError> different) {
   // Get the source code. This reads the data again, but it's safe because
   // all tests use memory file system.
-  var sourceCode = unit.element.source.contents.data;
+  var sourceCode =
+      resolutionMap.elementForCompilationUnit(unit).source.contents.data;
 
   String formatActualError(AnalysisError error) {
     int offset = error.offset;
     int length = error.length;
-    var span = _createSpanHelper(
-        unit.lineInfo, offset, unit.element.source, sourceCode,
+    var span = _createSpanHelper(unit.lineInfo, offset,
+        resolutionMap.elementForCompilationUnit(unit).source, sourceCode,
         end: offset + length);
     var levelName = _errorSeverity(context, error).displayName;
     return '@$offset $levelName:${_errorCodeName(error.errorCode)}\n' +
@@ -298,8 +301,8 @@ void _reportFailure(
 
   String formatExpectedError(_ErrorExpectation error) {
     int offset = error.offset;
-    var span = _createSpanHelper(
-        unit.lineInfo, offset, unit.element.source, sourceCode);
+    var span = _createSpanHelper(unit.lineInfo, offset,
+        resolutionMap.elementForCompilationUnit(unit).source, sourceCode);
     var severity = error.severity.displayName;
     return '@$offset $severity:${error.typeName}\n' + span.message('');
   }