Move resolveRelativeUri into front_end.

pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart

Index: pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart
diff --git a/pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart b/pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart
index 88ac8ecc2d2c534f7a56c3de6e6c08afe6189e50..a9bafc0b728035c368d24cc96ea5411c2dd91285 100644
--- a/pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart
+++ b/pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart
@@ -13,12 +13,12 @@ import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
-import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/util/absolute_path.dart';
 import 'package:front_end/incremental_resolved_ast_generator.dart';
 import 'package:front_end/src/base/file_repository.dart';
 import 'package:front_end/src/base/processed_options.dart';
+import 'package:front_end/src/base/resolve_relative_uri.dart';
 import 'package:front_end/src/base/source.dart';
 import 'package:front_end/src/dependency_grapher_impl.dart';
 import 'package:path/src/context.dart';