Use FileSystem to read files in SourceLoader and TranslateUri.

pkg/analyzer/lib/src/fasta/analyzer_target.dart

Index: pkg/analyzer/lib/src/fasta/analyzer_target.dart
diff --git a/pkg/analyzer/lib/src/fasta/analyzer_target.dart b/pkg/analyzer/lib/src/fasta/analyzer_target.dart
index 29eb092b7cd32814d0128183ce03912e8ca92202..77b3e5ee55dfe3136df745724cb2de8fe2771790 100644
--- a/pkg/analyzer/lib/src/fasta/analyzer_target.dart
+++ b/pkg/analyzer/lib/src/fasta/analyzer_target.dart
@@ -4,6 +4,7 @@
 
 library fasta.analyzer_target;
 
+import 'package:front_end/physical_file_system.dart';
 import 'package:kernel/ast.dart' show Library, Source;
 
 import 'package:front_end/src/fasta/kernel/kernel_target.dart'
@@ -19,7 +20,8 @@ class AnalyzerTarget extends KernelTarget {
   AnalyzerTarget(
       DillTarget dillTarget, TranslateUri uriTranslator, bool strongMode,
       [Map<String, Source> uriToSource])
-      : super(dillTarget, uriTranslator, strongMode, uriToSource);
+      : super(PhysicalFileSystem.instance, dillTarget, uriTranslator,
+            strongMode, uriToSource);
 
   @override
   AnalyzerLoader<Library> createLoader() => new AnalyzerLoader<Library>(this);