Run dartfmt on all files under runtime.

runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart

Index: runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart
diff --git a/runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart b/runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart
index 6bf7b7135c4f78cfb7a64ed1bc1885d71c3dde20..b6c9b0acc465ad17882e78b25de0ceb986669293 100644
--- a/runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart
+++ b/runtime/observatory/tests/observatory_ui/retaining_path/element_test.dart
@@ -27,18 +27,16 @@ main() {
   });
   test('elements created after attachment', () async {
     const source = const InstanceRefMock(id: 'source-id', name: 'source_name');
-    const path = const RetainingPathMock(elements: const [
-      const RetainingPathItemMock(source: source)
-    ]);
+    const path = const RetainingPathMock(
+        elements: const [const RetainingPathItemMock(source: source)]);
     bool invoked = false;
     final paths = new RetainingPathRepositoryMock(
-      getter: expectAsync((i, id) async {
-        expect(i, equals(isolate));
-        expect(id, equals(object.id));
-        invoked = true;
-        return path;
-      }, count: 1)
-    );
+        getter: expectAsync((i, id) async {
+      expect(i, equals(isolate));
+      expect(id, equals(object.id));
+      invoked = true;
+      return path;
+    }, count: 1));
     final instances = new InstanceRepositoryMock();
     final e = new RetainingPathElement(isolate, object, paths, instances);
     document.body.append(e);