Add Resource.delete() method.

pkg/analyzer/test/file_system/physical_resource_provider_test.dart

Index: pkg/analyzer/test/file_system/physical_resource_provider_test.dart
diff --git a/pkg/analyzer/test/file_system/physical_resource_provider_test.dart b/pkg/analyzer/test/file_system/physical_resource_provider_test.dart
index 1319defb9386dae1cd0d82dfb22be44bcad8ed4d..790eff7dcb11780f363573dc6ae0ee411bbe7c3f 100644
--- a/pkg/analyzer/test/file_system/physical_resource_provider_test.dart
+++ b/pkg/analyzer/test/file_system/physical_resource_provider_test.dart
@@ -50,6 +50,14 @@ class FileTest extends _BaseTest {
     expect(source.contents.data, 'contents');
   }
 
+  void test_delete() {
+    new io.File(path).writeAsStringSync('contents');
+    expect(file.exists, isTrue);
+    // delete
+    file.delete();
+    expect(file.exists, isFalse);
+  }
+
   void test_equals_differentPaths() {
     String path2 = join(tempPath, 'file2.txt');
     File file2 = PhysicalResourceProvider.INSTANCE.getResource(path2);
@@ -222,6 +230,16 @@ class FolderTest extends _BaseTest {
     expect(folder.contains(path), isFalse);
   }
 
+  void test_delete() {
+    new io.File(join(path, 'myFile')).createSync();
+    var child = folder.getChild('myFile');
+    expect(child, _isFile);
+    expect(child.exists, isTrue);
+    // delete "folder"
+    folder.delete();
+    expect(child.exists, isFalse);
+  }
+
   void test_equals_differentPaths() {
     String path2 = join(tempPath, 'folder2');
     new io.Directory(path2).createSync();