Expose clipBehavior to more buttons (#20538)

This allows developers to control the clipBehavior of those buttons.

packages/flutter/lib/src/material/flat_button.dart

@@ -38,6 +38,8 @@ import 'theme_data.dart';
 /// Flat buttons have a minimum size of 88.0 by 36.0 which can be overidden
 /// with [ButtonTheme].
 ///
+/// The [clipBehavior] argument must not be null.
+///
 /// See also:
 ///
 ///  * [RaisedButton], a filled button whose material elevates when pressed.
@@ -63,9 +65,10 @@ class FlatButton extends StatelessWidget {
     this.colorBrightness,
     this.padding,
     this.shape,
+    this.clipBehavior = Clip.none,
     this.materialTapTargetSize,
     @required this.child,
-  }) : super(key: key);
+  }) : assert(clipBehavior != null), super(key: key);
 
   /// Create a text button from a pair of widgets that serve as the button's
   /// [icon] and [label].
@@ -73,7 +76,7 @@ class FlatButton extends StatelessWidget {
   /// The icon and label are arranged in a row and padded by 12 logical pixels
   /// at the start, and 16 at the end, with an 8 pixel gap in between.
   ///
-  /// The [icon] and [label] arguments must not be null.
+  /// The [icon], [label], and [clipBehavior] arguments must not be null.
   FlatButton.icon({
     Key key,
     @required this.onPressed,
@@ -87,11 +90,13 @@ class FlatButton extends StatelessWidget {
     this.splashColor,
     this.colorBrightness,
     this.shape,
+    this.clipBehavior = Clip.none,
     this.materialTapTargetSize,
     @required Widget icon,
     @required Widget label,
   }) : assert(icon != null),
        assert(label != null),
+       assert(clipBehavior != null),
        padding = const EdgeInsetsDirectional.only(start: 12.0, end: 16.0),
        child = new Row(
          mainAxisSize: MainAxisSize.min,
@@ -221,6 +226,9 @@ class FlatButton extends StatelessWidget {
   /// shape as well.
   final ShapeBorder shape;
 
+  /// {@macro flutter.widgets.Clip}
+  final Clip clipBehavior;
+
   Brightness _getBrightness(ThemeData theme) {
     return colorBrightness ?? theme.brightness;
   }
@@ -306,6 +314,7 @@ class FlatButton extends StatelessWidget {
       padding: padding ?? buttonTheme.padding,
       constraints: buttonTheme.constraints,
       shape: shape ?? buttonTheme.shape,
+      clipBehavior: clipBehavior,
       child: child,
     );
   }

packages/flutter/lib/src/material/floating_action_button.dart

@@ -57,7 +57,7 @@ class _DefaultHeroTag {
 class FloatingActionButton extends StatefulWidget {
   /// Creates a circular floating action button.
   ///
-  /// The [elevation], [highlightElevation], [mini], and [shape]
+  /// The [elevation], [highlightElevation], [mini], [shape], and [clipBehavior]
   /// arguments must not be null.
   const FloatingActionButton({
     Key key,
@@ -71,6 +71,7 @@ class FloatingActionButton extends StatefulWidget {
     @required this.onPressed,
     this.mini = false,
     this.shape = const CircleBorder(),
+    this.clipBehavior = Clip.none,
     this.materialTapTargetSize,
     this.isExtended = false,
   }) :  assert(elevation != null),
@@ -84,7 +85,7 @@ class FloatingActionButton extends StatefulWidget {
   /// Creates a wider [StadiumBorder] shaped floating action button with both
   /// an [icon] and a [label].
   ///
-  /// The [label], [icon], [elevation], [highlightElevation]
+  /// The [label], [icon], [elevation], [highlightElevation], [clipBehavior]
   /// and [shape] arguments must not be null.
   FloatingActionButton.extended({
     Key key,
@@ -98,12 +99,14 @@ class FloatingActionButton extends StatefulWidget {
     this.shape = const StadiumBorder(),
     this.isExtended = true,
     this.materialTapTargetSize,
+    this.clipBehavior = Clip.none,
     @required Widget icon,
     @required Widget label,
   }) :  assert(elevation != null),
         assert(highlightElevation != null),
         assert(shape != null),
         assert(isExtended != null),
+        assert(clipBehavior != null),
         _sizeConstraints = _kExtendedSizeConstraints,
         mini = false,
         child = new _ChildOverflowBox(
@@ -193,6 +196,9 @@ class FloatingActionButton extends StatefulWidget {
   /// shape as well.
   final ShapeBorder shape;
 
+  /// {@macro flutter.widgets.Clip}
+  final Clip clipBehavior;
+
   /// True if this is an "extended" floating action button.
   ///
   /// Typically [extended] buttons have a [StadiumBorder] [shape]
@@ -265,6 +271,7 @@ class _FloatingActionButtonState extends State<FloatingActionButton> {
         letterSpacing: 1.2,
       ),
       shape: widget.shape,
+      clipBehavior: widget.clipBehavior,
       child: result,
     );