Throw FileSystemException from FileSystemEntity methods.

pkg/front_end/lib/physical_file_system.dart

Index: pkg/front_end/lib/physical_file_system.dart
diff --git a/pkg/front_end/lib/physical_file_system.dart b/pkg/front_end/lib/physical_file_system.dart
index a81a44dfea7c9850aebde4edd92e6e6e8543aa54..b00ad8c79b35f7713ba207bc93c8ec220d4fb2f4 100644
--- a/pkg/front_end/lib/physical_file_system.dart
+++ b/pkg/front_end/lib/physical_file_system.dart
@@ -43,12 +43,6 @@ class _PhysicalFileSystemEntity implements FileSystemEntity {
       other is _PhysicalFileSystemEntity && other.uri == uri;
 
   @override
-  Future<List<int>> readAsBytes() => new io.File.fromUri(uri).readAsBytes();
-
-  @override
-  Future<String> readAsString() => new io.File.fromUri(uri).readAsString();
-
-  @override
   Future<bool> exists() async {
     if (await io.FileSystemEntity.isFile(uri.toFilePath())) {
       return new io.File.fromUri(uri).exists();
@@ -58,5 +52,29 @@ class _PhysicalFileSystemEntity implements FileSystemEntity {
   }
 
   @override
-  Future<DateTime> lastModified() => new io.File.fromUri(uri).lastModified();
+  Future<DateTime> lastModified() async {
+    try {
+      return await new io.File.fromUri(uri).lastModified();
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(uri, exception.message);

[Paul Berry, 2017/05/07 14:06:49]

The logic you're removing from
pkg/front_end/lib/src/fasta/source/source_loader.dart prefers e.osError?.message
when available.  Should we replicate that logic here?

[scheglov, 2017/05/07 15:55:25]

Done.

+    }
+  }
+
+  @override
+  Future<List<int>> readAsBytes() async {
+    try {
+      return await new io.File.fromUri(uri).readAsBytes();
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(uri, exception.message);
+    }
+  }
+
+  @override
+  Future<String> readAsString() async {
+    try {
+      return await new io.File.fromUri(uri).readAsString();
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(uri, exception.message);
+    }
+  }
 }