Change MirrorSystem.libraries to Map<Uri, String>

sdk/lib/_internal/compiler/implementation/source_file_provider.dart

Index: sdk/lib/_internal/compiler/implementation/source_file_provider.dart
diff --git a/sdk/lib/_internal/compiler/implementation/source_file_provider.dart b/sdk/lib/_internal/compiler/implementation/source_file_provider.dart
index b75ba4ada2f2c760fff15ae8b0d920cdd8d1ced9..70659e075b330f37f6486c3efaf7f93a7b44bb27 100644
--- a/sdk/lib/_internal/compiler/implementation/source_file_provider.dart
+++ b/sdk/lib/_internal/compiler/implementation/source_file_provider.dart
@@ -27,7 +27,7 @@ String readAll(String filename) {
 
 class SourceFileProvider {
   bool isWindows = (Platform.operatingSystem == 'windows');
-  Uri cwd = getCurrentDirectory();
+  Uri cwd = currentDirectory;
   Map<String, SourceFile> sourceFiles = <String, SourceFile>{};
   int dartCharactersRead = 0;
 
@@ -43,8 +43,8 @@ class SourceFileProvider {
             '(${ex.osError}).';
     }
     dartCharactersRead += source.length;
-    sourceFiles[resourceUri.toString()] =
-      new SourceFile(relativize(cwd, resourceUri, isWindows), source);
+    sourceFiles[resourceUri.toString()] = new SourceFile(
+        relativize(cwd, resourceUri, isWindows), source);
     return new Future.value(source);
   }
 }