Rename Stack.sizing to Stack.fit (#9615)

The enum is called StackFit, so the property name "fit" makes more sense.

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

@@ -429,7 +429,7 @@ class InputDecorator extends StatelessWidget {
     }
 
     final Widget stack = new Stack(
-      sizing: StackFit.passthrough,
+      fit: StackFit.passthrough,
       children: stackChildren
     );
 

packages/flutter/lib/src/rendering/stack.dart

@@ -202,7 +202,7 @@ class StackParentData extends ContainerBoxParentDataMixin<RenderBox> {
 
 /// How to size the non-positioned children of a [Stack].
 ///
-/// This enum is used with [Stack.sizing] and [RenderStack.sizing] to control
+/// This enum is used with [Stack.fit] and [RenderStack.fit] to control
 /// how the [BoxConstraints] passed from the stack's parent to the stack's child
 /// are adjusted.
 ///
@@ -298,13 +298,13 @@ class RenderStack extends RenderBox
   RenderStack({
     List<RenderBox> children,
     FractionalOffset alignment: FractionalOffset.center,
-    StackFit sizing: StackFit.loose,
+    StackFit fit: StackFit.loose,
     Overflow overflow: Overflow.clip
   }) : _alignment = alignment,
-       _sizing = sizing,
+       _fit = fit,
        _overflow = overflow {
     assert(alignment != null);
-    assert(sizing != null);
+    assert(fit != null);
     assert(overflow != null);
     addAll(children);
   }
@@ -338,12 +338,12 @@ class RenderStack extends RenderBox
   /// The constraints passed into the [RenderStack] from its parent are either
   /// loosened ([StackFit.loose]) or tightened to their biggest size
   /// ([StackFit.expand]).
-  StackFit get sizing => _sizing;
-  StackFit _sizing;
-  set sizing(StackFit value) {
+  StackFit get fit => _fit;
+  StackFit _fit;
+  set fit(StackFit value) {
     assert(value != null);
-    if (_sizing != value) {
-      _sizing = value;
+    if (_fit != value) {
+      _fit = value;
       markNeedsLayout();
     }
   }
@@ -409,8 +409,8 @@ class RenderStack extends RenderBox
     double height = constraints.minHeight;
 
     BoxConstraints nonPositionedConstraints;
-    assert(sizing != null);
-    switch (sizing) {
+    assert(fit != null);
+    switch (fit) {
       case StackFit.loose:
         nonPositionedConstraints = constraints.loosen();
         break;

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

@@ -1648,7 +1648,7 @@ class Stack extends MultiChildRenderObjectWidget {
   Stack({
     Key key,
     this.alignment: FractionalOffset.topLeft,
-    this.sizing: StackFit.loose,
+    this.fit: StackFit.loose,
     this.overflow: Overflow.clip,
     List<Widget> children: const <Widget>[],
   }) : super(key: key, children: children);
@@ -1666,7 +1666,7 @@ class Stack extends MultiChildRenderObjectWidget {
   /// The constraints passed into the [Stack] from its parent are either
   /// loosened ([StackFit.loose]) or tightened to their biggest size
   /// ([StackFit.expand]).
-  final StackFit sizing;
+  final StackFit fit;
 
   /// Whether overflowing children should be clipped. See [Overflow].
   ///
@@ -1678,7 +1678,7 @@ class Stack extends MultiChildRenderObjectWidget {
   RenderStack createRenderObject(BuildContext context) {
     return new RenderStack(
       alignment: alignment,
-      sizing: sizing,
+      fit: fit,
       overflow: overflow,
     );
   }
@@ -1687,7 +1687,7 @@ class Stack extends MultiChildRenderObjectWidget {
   void updateRenderObject(BuildContext context, RenderStack renderObject) {
     renderObject
       ..alignment = alignment
-      ..sizing = sizing
+      ..fit = fit
       ..overflow = overflow;
   }
 }
@@ -1710,7 +1710,7 @@ class IndexedStack extends Stack {
     StackFit sizing: StackFit.loose,
     this.index: 0,
     List<Widget> children: const <Widget>[],
-  }) : super(key: key, alignment: alignment, sizing: sizing, children: children);
+  }) : super(key: key, alignment: alignment, fit: sizing, children: children);
 
   /// The index of the child to show.
   final int index;

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

@@ -362,7 +362,7 @@ class OverlayState extends State<Overlay> with TickerProviderStateMixin {
     }
     return new _Theatre(
       onstage: new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: onstageChildren.reversed.toList(growable: false),
       ),
       offstage: offstageChildren,

packages/flutter/test/widgets/semantics_4_test.dart

@@ -22,7 +22,7 @@ void main() {
     //
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           const Semantics(
             label: 'L1',
@@ -30,7 +30,7 @@ void main() {
           new Semantics(
             label: 'L2',
             child: new Stack(
-              sizing: StackFit.expand,
+              fit: StackFit.expand,
               children: <Widget>[
                 const Semantics(
                   checked: true,
@@ -78,7 +78,7 @@ void main() {
     //
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           const Semantics(
             label: 'L1',
@@ -86,7 +86,7 @@ void main() {
           new Semantics(
             label: 'L2',
             child: new Stack(
-              sizing: StackFit.expand,
+              fit: StackFit.expand,
               children: <Widget>[
                 const Semantics(
                   checked: true,
@@ -122,13 +122,13 @@ void main() {
     //
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           const Semantics(),
           new Semantics(
             label: 'L2',
             child: new Stack(
-              sizing: StackFit.expand,
+              fit: StackFit.expand,
               children: <Widget>[
                 const Semantics(
                   checked: true,

packages/flutter/test/widgets/semantics_5_test.dart

@@ -14,7 +14,7 @@ void main() {
 
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           const Semantics(
             // this tests that empty nodes disappear

packages/flutter/test/widgets/semantics_7_test.dart

@@ -19,7 +19,7 @@ void main() {
     label = '1';
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           new MergeSemantics(
             child: new Semantics(
@@ -33,7 +33,7 @@ void main() {
           ),
           new MergeSemantics(
             child: new Stack(
-              sizing: StackFit.expand,
+              fit: StackFit.expand,
               children: <Widget>[
                 const Semantics(
                   checked: true,
@@ -71,7 +71,7 @@ void main() {
     label = '2';
     await tester.pumpWidget(
       new Stack(
-        sizing: StackFit.expand,
+        fit: StackFit.expand,
         children: <Widget>[
           new MergeSemantics(
             child: new Semantics(
@@ -85,7 +85,7 @@ void main() {
           ),
           new MergeSemantics(
             child: new Stack(
-              sizing: StackFit.expand,
+              fit: StackFit.expand,
               children: <Widget>[
                 const Semantics(
                   checked: true,

packages/flutter/test/widgets/stack_test.dart

@@ -383,7 +383,7 @@ void main() {
             maxHeight: 7.0,
           ),
           child: new Stack(
-            sizing: sizing,
+            fit: sizing,
             children: <Widget>[
               new LayoutBuilder(
                 builder: (BuildContext context, BoxConstraints constraints) {