Cleanup (#20754)

- remove an //ignore that is no longer needed
- fix some intrinsic methods that used the API incorrectly (shouldn't affect correctness but should make things a tiny bit more efficient)
- add some asserts to help track down bugs quicker
- update a TODO to point to the currently relevant bug
- fix some indenting
- improve the naming of some privates to improve readability

packages/flutter/lib/src/cupertino/segmented_control.dart

@@ -518,7 +518,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double minWidth = 0.0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData = child.parentData;
-      final double childWidth = child.computeMinIntrinsicWidth(height);
+      final double childWidth = child.getMinIntrinsicWidth(height);
       minWidth = math.max(minWidth, childWidth);
       child = childParentData.nextSibling;
     }
@@ -531,7 +531,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxWidth = 0.0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData = child.parentData;
-      final double childWidth = child.computeMaxIntrinsicWidth(height);
+      final double childWidth = child.getMaxIntrinsicWidth(height);
       maxWidth = math.max(maxWidth, childWidth);
       child = childParentData.nextSibling;
     }
@@ -544,7 +544,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double minHeight = 0.0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData = child.parentData;
-      final double childHeight = child.computeMinIntrinsicHeight(width);
+      final double childHeight = child.getMinIntrinsicHeight(width);
       minHeight = math.max(minHeight, childHeight);
       child = childParentData.nextSibling;
     }
@@ -557,7 +557,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxHeight = 0.0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData = child.parentData;
-      final double childHeight = child.computeMaxIntrinsicHeight(width);
+      final double childHeight = child.getMaxIntrinsicHeight(width);
       maxHeight = math.max(maxHeight, childHeight);
       child = childParentData.nextSibling;
     }

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

@@ -497,28 +497,28 @@ class _RenderInputPadding extends RenderShiftedBox {
   @override
   double computeMinIntrinsicWidth(double height) {
     if (child != null)
-      return math.max(child.computeMinIntrinsicWidth(height), minSize.width);
+      return math.max(child.getMinIntrinsicWidth(height), minSize.width);
     return 0.0;
   }
 
   @override
   double computeMinIntrinsicHeight(double width) {
     if (child != null)
-      return math.max(child.computeMinIntrinsicHeight(width), minSize.height);
+      return math.max(child.getMinIntrinsicHeight(width), minSize.height);
     return 0.0;
   }
 
   @override
   double computeMaxIntrinsicWidth(double height) {
     if (child != null)
-      return math.max(child.computeMaxIntrinsicWidth(height), minSize.width);
+      return math.max(child.getMaxIntrinsicWidth(height), minSize.width);
     return 0.0;
   }
 
   @override
   double computeMaxIntrinsicHeight(double width) {
     if (child != null)
-      return math.max(child.computeMaxIntrinsicHeight(width), minSize.height);
+      return math.max(child.getMaxIntrinsicHeight(width), minSize.height);
     return 0.0;
   }
 

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

@@ -144,7 +144,7 @@ class ExpansionPanelList extends StatefulWidget {
     this.expansionCallback,
     this.animationDuration = kThemeAnimationDuration,
     this.initialOpenPanelValue,
-  }) : children = children, //ignore:prefer_initializing_formals
+  }) : children = children, // ignore: prefer_initializing_formals
        assert(children != null),
        assert(animationDuration != null),
        _allowOnlyOnePanelOpen = true,

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

@@ -744,6 +744,7 @@ class _TabBarState extends State<TabBar> {
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
+    assert(debugCheckHasMaterial(context));
     _updateTabController();
     _initIndicatorPainter();
   }

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

@@ -42,8 +42,7 @@ class RenderProxyBox extends RenderBox with RenderObjectWithChildMixin<RenderBox
   /// Proxy render boxes are rarely created directly because they simply proxy
   /// the render box protocol to [child]. Instead, consider using one of the
   /// subclasses.
-  // TODO(a14n): Remove ignore once https://github.com/dart-lang/sdk/issues/30328 is fixed
-  RenderProxyBox([RenderBox child = null]) { //ignore: avoid_init_to_null
+  RenderProxyBox([RenderBox child]) {
     this.child = child;
   }
 }

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

@@ -328,7 +328,7 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin
 
   // SEMANTICS
 
-  final GlobalKey _excludableScrollSemanticsKey = new GlobalKey();
+  final GlobalKey _scrollSemanticsKey = new GlobalKey();
 
   @override
   @protected
@@ -504,8 +504,8 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin
     );
 
     if (!widget.excludeFromSemantics) {
-      result = new _ExcludableScrollSemantics(
-        key: _excludableScrollSemanticsKey,
+      result = new _ScrollSemantics(
+        key: _scrollSemanticsKey,
         child: result,
         position: position,
         allowImplicitScrolling: widget?.physics?.allowImplicitScrolling ?? false,
@@ -522,7 +522,7 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin
   }
 }
 
-/// With [_ExcludableScrollSemantics] certain child [SemanticsNode]s can be
+/// With [_ScrollSemantics] certain child [SemanticsNode]s can be
 /// excluded from the scrollable area for semantics purposes.
 ///
 /// Nodes, that are to be excluded, have to be tagged with
@@ -536,8 +536,8 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin
 /// node will contain all children, that are excluded from scrolling. The inner
 /// node, which is annotated with the scrolling actions, will house the
 /// scrollable children.
-class _ExcludableScrollSemantics extends SingleChildRenderObjectWidget {
-  const _ExcludableScrollSemantics({
+class _ScrollSemantics extends SingleChildRenderObjectWidget {
+  const _ScrollSemantics({
     Key key,
     @required this.position,
     @required this.allowImplicitScrolling,
@@ -548,25 +548,23 @@ class _ExcludableScrollSemantics extends SingleChildRenderObjectWidget {
   final bool allowImplicitScrolling;
 
   @override
-  _RenderExcludableScrollSemantics createRenderObject(BuildContext context) {
-    return new _RenderExcludableScrollSemantics(
+  _RenderScrollSemantics createRenderObject(BuildContext context) {
+    return new _RenderScrollSemantics(
       position: position,
       allowImplicitScrolling: allowImplicitScrolling,
     );
   }
 
-
-
   @override
-  void updateRenderObject(BuildContext context, _RenderExcludableScrollSemantics renderObject) {
+  void updateRenderObject(BuildContext context, _RenderScrollSemantics renderObject) {
     renderObject
       ..allowImplicitScrolling = allowImplicitScrolling
       ..position = position;
   }
 }
 
-class _RenderExcludableScrollSemantics extends RenderProxyBox {
-  _RenderExcludableScrollSemantics({
+class _RenderScrollSemantics extends RenderProxyBox {
+  _RenderScrollSemantics({
     @required ScrollPosition position,
     @required bool allowImplicitScrolling,
     RenderBox child,

packages/flutter/test/material/input_decorator_test.dart

@@ -66,10 +66,10 @@ InputBorder getBorder(WidgetTester tester) {
   if (!tester.any(findBorderPainter()))
     return null;
   final CustomPaint customPaint = tester.widget(findBorderPainter());
-  final dynamic/* _InputBorderPainter */ inputBorderPainter = customPaint.foregroundPainter;
-  final dynamic/*_InputBorderTween */ inputBorderTween = inputBorderPainter.border;
+  final dynamic/*_InputBorderPainter*/ inputBorderPainter = customPaint.foregroundPainter;
+  final dynamic/*_InputBorderTween*/ inputBorderTween = inputBorderPainter.border;
   final Animation<double> animation = inputBorderPainter.borderAnimation;
-  final dynamic/*_InputBorder */ border = inputBorderTween.evaluate(animation);
+  final dynamic/*_InputBorder*/ border = inputBorderTween.evaluate(animation);
   return border;
 }
 

packages/flutter/test/widgets/keep_alive_test.dart

@@ -226,7 +226,7 @@ void main() {
       '       │ diagnosis: insufficient data to draw conclusion (less than five\n'
       '       │   repaints)\n'
       '       │\n'
-      '       └─child: _RenderExcludableScrollSemantics#00000\n'
+      '       └─child: _RenderScrollSemantics#00000\n'
       '         │ parentData: <none> (can use size)\n'
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '         │ semantic boundary\n'
@@ -355,7 +355,7 @@ void main() {
       '       │ diagnosis: insufficient data to draw conclusion (less than five\n'
       '       │   repaints)\n'
       '       │\n'
-      '       └─child: _RenderExcludableScrollSemantics#00000\n'
+      '       └─child: _RenderScrollSemantics#00000\n'
       '         │ parentData: <none> (can use size)\n'
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '         │ semantic boundary\n'