Wrap dart:io exception in getChildren(), implement for the memory FS.

pkg/analyzer/lib/file_system/physical_file_system.dart

Index: pkg/analyzer/lib/file_system/physical_file_system.dart
diff --git a/pkg/analyzer/lib/file_system/physical_file_system.dart b/pkg/analyzer/lib/file_system/physical_file_system.dart
index 71c40203f74d8c2dad65a7e08f86cfcf989afe11..edec1ae6dfc99f7d78c931feaf89b9a6ce1e4efa 100644
--- a/pkg/analyzer/lib/file_system/physical_file_system.dart
+++ b/pkg/analyzer/lib/file_system/physical_file_system.dart
@@ -80,7 +80,7 @@ class _PhysicalFile extends _PhysicalResource implements File {
       io.File file = _entry as io.File;
       return file.lastModifiedSync().millisecondsSinceEpoch;
     } on io.FileSystemException catch (exception) {
-      throw new FileSystemException(path, exception.message);
+      throw new FileSystemException(exception.path, exception.message);
     }
   }
 
@@ -134,19 +134,23 @@ class _PhysicalFolder extends _PhysicalResource implements Folder {
 
   @override
   List<Resource> getChildren() {
-    List<Resource> children = <Resource>[];
-    io.Directory directory = _entry as io.Directory;
-    List<io.FileSystemEntity> entries = directory.listSync(recursive: false);
-    int numEntries = entries.length;
-    for (int i = 0; i < numEntries; i++) {
-      io.FileSystemEntity entity = entries[i];
-      if (entity is io.Directory) {
-        children.add(new _PhysicalFolder(entity));
-      } else if (entity is io.File) {
-        children.add(new _PhysicalFile(entity));
+    try {
+      List<Resource> children = <Resource>[];
+      io.Directory directory = _entry as io.Directory;
+      List<io.FileSystemEntity> entries = directory.listSync(recursive: false);
+      int numEntries = entries.length;
+      for (int i = 0; i < numEntries; i++) {
+        io.FileSystemEntity entity = entries[i];
+        if (entity is io.Directory) {
+          children.add(new _PhysicalFolder(entity));
+        } else if (entity is io.File) {
+          children.add(new _PhysicalFile(entity));
+        }
       }
+      return children;
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(exception.path, exception.message);
     }
-    return children;
   }
 
   @override