diff --git a/lib/ui/semantics.dart b/lib/ui/semantics.dart
index 542aba9fd862f..60e374991bf40 100644
--- a/lib/ui/semantics.dart
+++ b/lib/ui/semantics.dart
@@ -647,19 +647,21 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
   /// reading direction of all these strings is given by `textDirection`.
   ///
   /// The fields `textSelectionBase` and `textSelectionExtent` describe the
-  /// currently selected text within `value`.
+  /// currently selected text within `value`. A value of -1 indicates no
+  /// current text selection base or extent.
   ///
-  /// The field `maxValueLength` is used to indicate that an editable text field
-  /// has a limit on the number of characters entered. If it is -1 there is
-  /// no limit on the number of characters entered. The field
+  /// The field `maxValueLength` is used to indicate that an editable text
+  /// field has a limit on the number of characters entered. If it is -1 there
+  /// is no limit on the number of characters entered. The field
   /// `currentValueLength` indicates how much of that limit has already been
-  /// used up. When `maxValueLength` is set, `currentValueLength` must also be
-  /// set.
+  /// used up. When `maxValueLength` is >= 0, `currentValueLength` must also be
+  /// >= 0, otherwise it should be specified to be -1.
   ///
   /// The field `platformViewId` references the platform view, whose semantics
   /// nodes will be added as children to this node. If a platform view is
-  /// specified, `childrenInHitTestOrder` and `childrenInTraversalOrder` must be
-  /// empty.
+  /// specified, `childrenInHitTestOrder` and `childrenInTraversalOrder` must
+  /// be empty. A value of -1 indicates that this node is not associated with a
+  /// platform view.
   ///
   /// For scrollable nodes `scrollPosition` describes the current scroll
   /// position in logical pixel. `scrollExtentMax` and `scrollExtentMin`
@@ -684,32 +686,32 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
   /// node starts at `elevation` above the parent and ends at `elevation` +
   /// `thickness` above the parent.
   void updateNode({
-    int id,
-    int flags,
-    int actions,
-    int maxValueLength,
-    int currentValueLength,
-    int textSelectionBase,
-    int textSelectionExtent,
-    int platformViewId,
-    int scrollChildren,
-    int scrollIndex,
-    double scrollPosition,
-    double scrollExtentMax,
-    double scrollExtentMin,
-    double elevation,
-    double thickness,
-    Rect rect,
-    String label,
-    String hint,
-    String value,
-    String increasedValue,
-    String decreasedValue,
-    TextDirection textDirection,
-    Float64List transform,
-    Int32List childrenInTraversalOrder,
-    Int32List childrenInHitTestOrder,
-    Int32List additionalActions,
+    /*required*/ int/*!*/ id,
+    /*required*/ int/*!*/ flags,
+    /*required*/ int/*!*/ actions,
+    /*required*/ int/*!*/ maxValueLength,
+    /*required*/ int/*!*/ currentValueLength,
+    /*required*/ int/*!*/ textSelectionBase,
+    /*required*/ int/*!*/ textSelectionExtent,
+    /*required*/ int/*!*/ platformViewId,
+    /*required*/ int/*!*/ scrollChildren,
+    /*required*/ int/*!*/ scrollIndex,
+    /*required*/ double/*!*/ scrollPosition,
+    /*required*/ double/*!*/ scrollExtentMax,
+    /*required*/ double/*!*/ scrollExtentMin,
+    /*required*/ double/*!*/ elevation,
+    /*required*/ double/*!*/ thickness,
+    /*required*/ Rect/*!*/ rect,
+    /*required*/ String/*!*/ label,
+    /*required*/ String/*!*/ hint,
+    /*required*/ String/*!*/ value,
+    /*required*/ String/*!*/ increasedValue,
+    /*required*/ String/*!*/ decreasedValue,
+    TextDirection/*?*/ textDirection,
+    /*required*/ Float64List/*!*/ transform,
+    /*required*/ Int32List/*!*/ childrenInTraversalOrder,
+    /*required*/ Int32List/*!*/ childrenInHitTestOrder,
+    /*required*/ Int32List/*!*/ additionalActions,
   }) {
     assert(_matrix4IsValid(transform));
     assert(
@@ -749,35 +751,35 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     );
   }
   void _updateNode(
-    int id,
-    int flags,
-    int actions,
-    int maxValueLength,
-    int currentValueLength,
-    int textSelectionBase,
-    int textSelectionExtent,
-    int platformViewId,
-    int scrollChildren,
-    int scrollIndex,
-    double scrollPosition,
-    double scrollExtentMax,
-    double scrollExtentMin,
-    double left,
-    double top,
-    double right,
-    double bottom,
-    double elevation,
-    double thickness,
-    String label,
-    String hint,
-    String value,
-    String increasedValue,
-    String decreasedValue,
-    int textDirection,
-    Float64List transform,
-    Int32List childrenInTraversalOrder,
-    Int32List childrenInHitTestOrder,
-    Int32List additionalActions,
+    int/*!*/ id,
+    int/*!*/ flags,
+    int/*!*/ actions,
+    int/*!*/ maxValueLength,
+    int/*!*/ currentValueLength,
+    int/*!*/ textSelectionBase,
+    int/*!*/ textSelectionExtent,
+    int/*!*/ platformViewId,
+    int/*!*/ scrollChildren,
+    int/*!*/ scrollIndex,
+    double/*!*/ scrollPosition,
+    double/*!*/ scrollExtentMax,
+    double/*!*/ scrollExtentMin,
+    double/*!*/ left,
+    double/*!*/ top,
+    double/*!*/ right,
+    double/*!*/ bottom,
+    double/*!*/ elevation,
+    double/*!*/ thickness,
+    String/*!*/ label,
+    String/*!*/ hint,
+    String/*!*/ value,
+    String/*!*/ increasedValue,
+    String/*!*/ decreasedValue,
+    int/*!*/ textDirection,
+    Float64List/*!*/ transform,
+    Int32List/*!*/ childrenInTraversalOrder,
+    Int32List/*!*/ childrenInHitTestOrder,
+    Int32List/*!*/ additionalActions,
   ) native 'SemanticsUpdateBuilder_updateNode';
 
   /// Update the custom semantics action associated with the given `id`.
diff --git a/lib/web_ui/lib/src/ui/semantics.dart b/lib/web_ui/lib/src/ui/semantics.dart
index 2fafa93b9c0ca..8e242030c5d74 100644
--- a/lib/web_ui/lib/src/ui/semantics.dart
+++ b/lib/web_ui/lib/src/ui/semantics.dart
@@ -667,32 +667,32 @@ class SemanticsUpdateBuilder {
   /// The `transform` is a matrix that maps this node's coordinate system into
   /// its parent's coordinate system.
   void updateNode({
-    int id,
-    int flags,
-    int actions,
-    int maxValueLength,
-    int currentValueLength,
-    int textSelectionBase,
-    int textSelectionExtent,
-    int platformViewId,
-    int scrollChildren,
-    int scrollIndex,
-    double scrollPosition,
-    double scrollExtentMax,
-    double scrollExtentMin,
-    double elevation,
-    double thickness,
-    Rect rect,
-    String label,
-    String hint,
-    String value,
-    String increasedValue,
-    String decreasedValue,
-    TextDirection textDirection,
-    Float64List transform,
-    Int32List childrenInTraversalOrder,
-    Int32List childrenInHitTestOrder,
-    Int32List additionalActions,
+    /*required*/ int/*!*/ id,
+    /*required*/ int/*!*/ flags,
+    /*required*/ int/*!*/ actions,
+    /*required*/ int/*!*/ maxValueLength,
+    /*required*/ int/*!*/ currentValueLength,
+    /*required*/ int/*!*/ textSelectionBase,
+    /*required*/ int/*!*/ textSelectionExtent,
+    /*required*/ int/*!*/ platformViewId,
+    /*required*/ int/*!*/ scrollChildren,
+    /*required*/ int/*!*/ scrollIndex,
+    /*required*/ double/*!*/ scrollPosition,
+    /*required*/ double/*!*/ scrollExtentMax,
+    /*required*/ double/*!*/ scrollExtentMin,
+    /*required*/ double/*!*/ elevation,
+    /*required*/ double/*!*/ thickness,
+    /*required*/ Rect/*!*/ rect,
+    /*required*/ String/*!*/ label,
+    /*required*/ String/*!*/ hint,
+    /*required*/ String/*!*/ value,
+    /*required*/ String/*!*/ increasedValue,
+    /*required*/ String/*!*/ decreasedValue,
+    TextDirection/*?*/ textDirection,
+    /*required*/ Float64List/*!*/ transform,
+    /*required*/ Int32List/*!*/ childrenInTraversalOrder,
+    /*required*/ Int32List/*!*/ childrenInHitTestOrder,
+    /*required*/ Int32List/*!*/ additionalActions,
   }) {
     if (transform.length != 16)
       throw ArgumentError('transform argument must have 16 entries.');