Consolidate duplicate code for resloving URIs.

pkg/analyzer/lib/src/summary/package_bundle_reader.dart

 import 'dart:io' as io;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
@@ skipping 145 matching lines @@
   UriKind get uriKind => UriKind.PACKAGE_URI;
 
   @override
   bool operator ==(Object object) =>
       object is InSummarySource && object.uri == uri;
 
   @override
   bool exists() => true;
 
   @override
-  Uri resolveRelativeUri(Uri relativeUri) {
-    Uri baseUri = uri;
-    return baseUri.resolveUri(relativeUri);
-  }
-
-  @override
   String toString() => uri.toString();
 }
 
 /**
  * A [SummaryDataStore] is a container for the data extracted from a set of
  * summary package bundles.  It contains maps which can be used to find linked
  * and unlinked summaries by URI.
  */
 class SummaryDataStore {
   /**
@@ skipping 70 matching lines @@
  * also provides [summaryPath].
  */
 class _InSummaryFallbackSource extends FileBasedSource
     implements InSummarySource {
   @override
   final String summaryPath;
 
   _InSummaryFallbackSource(JavaFile file, Uri uri, this.summaryPath)
       : super(file, uri);
 }