prefer_const_constructor in packages/flutter/lib (#7179)

packages/flutter/lib/src/cassowary/solver.dart

@@ -14,7 +14,7 @@ import 'term.dart';
 enum _SymbolType { invalid, external, slack, error, dummy, }
 
 class _Symbol {
-  const _Symbol(this.type);
+  _Symbol(this.type);
 
   final _SymbolType type;
 }

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

@@ -393,7 +393,7 @@ class _LicensePageState extends State<LicensePage> {
           ),
           child: new Text(
             license.packages.join(', '),
-            style: new TextStyle(fontWeight: FontWeight.bold),
+            style: const TextStyle(fontWeight: FontWeight.bold),
             textAlign: TextAlign.center
           )
         ));
@@ -403,7 +403,7 @@ class _LicensePageState extends State<LicensePage> {
               padding: const EdgeInsets.only(top: 16.0),
               child: new Text(
                 paragraph.text,
-                style: new TextStyle(fontWeight: FontWeight.bold),
+                style: const TextStyle(fontWeight: FontWeight.bold),
                 textAlign: TextAlign.center
               )
             ));

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

@@ -426,7 +426,7 @@ class BottomNavigationBarState extends State<BottomNavigationBar> with TickerPro
                           opacity: animations[i],
                           child: new DefaultTextStyle.merge(
                             context: context,
-                            style: new TextStyle(
+                            style: const TextStyle(
                               fontSize: 14.0,
                               color: Colors.white
                             ),

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

@@ -203,9 +203,9 @@ class _RenderCheckbox extends RenderToggleable {
         ..style = PaintingStyle.stroke
         ..strokeWidth = _kStrokeWidth;
       Path path = new Path();
-      Point start = new Point(_kEdgeSize * 0.15, _kEdgeSize * 0.45);
-      Point mid = new Point(_kEdgeSize * 0.4, _kEdgeSize * 0.7);
-      Point end = new Point(_kEdgeSize * 0.85, _kEdgeSize * 0.25);
+      Point start = const Point(_kEdgeSize * 0.15, _kEdgeSize * 0.45);
+      Point mid = const Point(_kEdgeSize * 0.4, _kEdgeSize * 0.7);
+      Point end = const Point(_kEdgeSize * 0.85, _kEdgeSize * 0.25);
       Point drawStart = Point.lerp(start, mid, 1.0 - value);
       Point drawEnd = Point.lerp(mid, end, value);
       path.moveTo(offsetX + drawStart.x, offsetY + drawStart.y);

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

@@ -95,7 +95,7 @@ class Chip extends StatelessWidget {
           message: 'Delete "$label"',
           child: new Container(
             padding: const EdgeInsets.symmetric(horizontal: 4.0),
-            child: new Icon(
+            child: const Icon(
               Icons.cancel,
               size: 18.0,
               color: Colors.black54

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

@@ -126,7 +126,7 @@ class GridTileBar extends StatelessWidget {
         data: darkTheme,
         child: new IconTheme.merge(
           context: context,
-          data: new IconThemeData(color: Colors.white),
+          data: const IconThemeData(color: Colors.white),
           child: new Row(
             crossAxisAlignment: CrossAxisAlignment.center,
             children: children