Revert "Extend file-system abstraction with a couple methods, remove context."

pkg/front_end/test/physical_file_system_test.dart

Index: pkg/front_end/test/physical_file_system_test.dart
diff --git a/pkg/front_end/test/physical_file_system_test.dart b/pkg/front_end/test/physical_file_system_test.dart
index c3194bde4199e9b3e06dd977ab86f66811def5c6..d1a026bbe8550006ae2d4627923b2ebdcef8f120 100644
--- a/pkg/front_end/test/physical_file_system_test.dart
+++ b/pkg/front_end/test/physical_file_system_test.dart
@@ -19,7 +19,6 @@ main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PhysicalFileSystemTest);
     defineReflectiveTests(FileTest);
-    defineReflectiveTests(DirectoryTest);
   });
 }
 
@@ -87,71 +86,6 @@ class FileTest extends _BaseTest {
   test_uri() {
     expect(file.uri, p.toUri(path));
   }
-
-  test_exists_doesNotExist() async {
-    expect(await file.exists(), isFalse);
-  }
-
-  test_exists_fileExists() async {
-    new io.File(path).writeAsStringSync('contents');
-    expect(await file.exists(), isTrue);
-  }
-
-  test_lastModified_increasesOnEachChange() async {
-    new io.File(path).writeAsStringSync('contents1');
-    var mod1 = await file.lastModified();
-
-    // Pause to ensure the file-system time-stamps are different.
-    await new Future.delayed(new Duration(seconds: 1));
-    new io.File(path).writeAsStringSync('contents2');
-    var mod2 = await file.lastModified();
-    expect(mod2.isAfter(mod1), isTrue);
-
-    await new Future.delayed(new Duration(seconds: 1));
-    var path2 = p.join(tempPath, 'file2.txt');
-    new io.File(path2).writeAsStringSync('contents2');
-    var file2 = entityForPath(path2);
-    var mod3 = await file2.lastModified();
-    expect(mod3.isAfter(mod2), isTrue);
-  }
-}
-
-@reflectiveTest
-class DirectoryTest extends _BaseTest {
-  String path;
-  FileSystemEntity dir;
-
-  setUp() {
-    super.setUp();
-    path = p.join(tempPath, 'dir');
-    dir = PhysicalFileSystem.instance.entityForUri(p.toUri(path));
-  }
-
-  test_equals_differentPaths() {
-    expect(dir == entityForPath(p.join(tempPath, 'dir2')), isFalse);
-  }
-
-  test_equals_samePath() {
-    expect(dir == entityForPath(p.join(tempPath, 'dir')), isTrue);
-  }
-
-  test_readAsBytes() async {
-    new io.Directory(path).create();
-    expect(dir.readAsBytes(), throwsException);
-  }
-
-  test_uri() {
-    expect(dir.uri, p.toUri(path));
-  }
-
-  test_exists_doesNotExist() async {
-    expect(await dir.exists(), isFalse);
-  }
-
-  test_exists_directoryExists() async {
-    new io.Directory(path).create();
-    expect(await dir.exists(), isTrue);
-  }
 }
 
 @reflectiveTest