Use package: URIs for files in lib

pkg/analyzer/test/source/package_map_resolver_test.dart

Index: pkg/analyzer/test/source/package_map_resolver_test.dart
diff --git a/pkg/analyzer/test/source/package_map_resolver_test.dart b/pkg/analyzer/test/source/package_map_resolver_test.dart
index a12e361680fd6e6e7c254957bd3e896ef292f9d1..0869c56637a2d39bdbab4a0279ca3bc3eda2c9c6 100644
--- a/pkg/analyzer/test/source/package_map_resolver_test.dart
+++ b/pkg/analyzer/test/source/package_map_resolver_test.dart
@@ -162,13 +162,13 @@ class _PackageMapUriResolverTest {
       Source source = _createFileSource('/pkgA/lib/libA.dart');
       Uri uri = resolver.restoreAbsolute(source);
       expect(uri, isNotNull);
-      expect(uri.path, 'package:pkgA/libA.dart');
+      expect(uri.toString(), 'package:pkgA/libA.dart');
     }
     {
       Source source = _createFileSource('/pkgB/lib/src/libB.dart');
       Uri uri = resolver.restoreAbsolute(source);
       expect(uri, isNotNull);
-      expect(uri.path, 'package:pkgB/src/libB.dart');
+      expect(uri.toString(), 'package:pkgB/src/libB.dart');
     }
     {
       Source source = _createFileSource('/no/such/file');