Fix "edit.format" to follow protocol when there is no selection.

pkg/analysis_server/test/edit/format_test.dart

Index: pkg/analysis_server/test/edit/format_test.dart
diff --git a/pkg/analysis_server/test/edit/format_test.dart b/pkg/analysis_server/test/edit/format_test.dart
index 6a8e870e099a56719e7252efc45d765546dc2b33..1bd9f709d35503b5522f35cddb4eca40e486dabd 100644
--- a/pkg/analysis_server/test/edit/format_test.dart
+++ b/pkg/analysis_server/test/edit/format_test.dart
@@ -46,6 +46,26 @@ main() {
     });
   }
 
+  Future test_formatNoSelection() async {
+    addTestFile('''
+main() { int x = 3; }
+''');
+    await waitForTasksFinished();
+    EditFormatResult formatResult = _formatAt(0, 0);
+
+    expect(formatResult.edits, isNotNull);
+    expect(formatResult.edits, hasLength(1));
+
+    SourceEdit edit = formatResult.edits[0];
+    expect(edit.replacement, equals('''
+main() {
+  int x = 3;
+}
+'''));
+    expect(formatResult.selectionOffset, equals(0));
+    expect(formatResult.selectionLength, equals(0));
+  }
+
   Future test_formatSimple() {
     addTestFile('''
 main() { int x = 3; }