Clean up a few stale TODOs. (#6698)

packages/flutter/lib/src/widgets/editable.dart

@@ -118,14 +118,12 @@ class InputValue {
   }
 }
 
-/// A basic single-line input control.
+/// A basic text input control.
 ///
 /// This control is not intended to be used directly. Instead, consider using
 /// [Input], which provides focus management and material design.
-//
-// TODO(mpcomplete): rename RawInput since it can span multiple lines.
 class RawInput extends Scrollable {
-  /// Creates a basic single-line input control.
+  /// Creates a basic text input control.
   ///
   /// The [value] argument must not be null.
   RawInput({

packages/flutter/lib/src/widgets/text_selection.dart

@@ -14,7 +14,6 @@ import 'gesture_detector.dart';
 import 'overlay.dart';
 import 'transitions.dart';
 
-// TODO(mpcomplete): Need one for [collapsed].
 /// Which type of selection handle to be displayed.
 ///
 /// With mixed-direction text, both handles may be the same type. Examples: