Delete unreachable default clauses.

The Dart analyzer will soon be changed so that if the `default` clause
of a `switch` statement is determined to be unreachable by the
exhaustiveness checker, a new warning of type
`unreachable_switch_default` will be issued. This parallels the
behavior of the existing `unreachable_switch_case` warning, which is
issued whenever a `case` clause of a `switch` statement is determined
to be unreachable. For details see
dart-lang/sdk#54575.

This PR deletes unreachable `default` clauses from `devtools` now, to
avoid a spurious warning when the analyzer change lands.

Author: stereotype441

packages/devtools_app/lib/src/screens/app_size/app_size_controller.dart

@@ -37,7 +37,6 @@ enum DiffTreeType {
       case DiffTreeType.decreaseOnly:
         return 'Decrease Only';
       case DiffTreeType.combined:
-      default:
         return 'Combined';
     }
   }
@@ -55,7 +54,6 @@ enum AppUnit {
       case AppUnit.mainOnly:
         return _mainNodeName;
       case AppUnit.entireApp:
-      default:
         return _entireAppNodeName;
     }
   }
@@ -185,7 +183,6 @@ class AppSizeController {
       case AppUnit.deferredOnly:
         return _deferredDiffTreeMap;
       case AppUnit.entireApp:
-      default:
         return _diffTreeMap;
     }
   }
@@ -205,8 +202,6 @@ class AppSizeController {
         return diffMap.decreaseOnly;
       case DiffTreeType.combined:
         return diffMap.combined;
-      default:
-        return diffMap.combined;
     }
   }
 
@@ -221,7 +216,6 @@ class AppSizeController {
       case AppUnit.mainOnly:
         return _mainOnly;
       case AppUnit.entireApp:
-      default:
         return _entireApp;
     }
   }

packages/devtools_app/lib/src/screens/inspector/layout_explorer/flex/utils.dart

@@ -197,7 +197,6 @@ extension AxisExtension on Axis {
       case Axis.horizontal:
         return 'Row';
       case Axis.vertical:
-      default:
         return 'Column';
     }
   }

packages/devtools_app/lib/src/screens/inspector_v2/layout_explorer/flex/utils.dart

@@ -197,7 +197,6 @@ extension AxisExtension on Axis {
       case Axis.horizontal:
         return 'Row';
       case Axis.vertical:
-      default:
         return 'Column';
     }
   }

packages/devtools_app/lib/src/shared/charts/chart.dart

@@ -698,10 +698,6 @@ class ChartPainter extends CustomPainter {
         );
         canvas.drawPath(path, paintFirst);
         break;
-      default:
-        final message = 'Unknown symbol ${characteristics.symbol}';
-        assert(false, message);
-        _log.shout(message);
     }
   }
 

packages/devtools_app/lib/src/shared/charts/treemap.dart

@@ -123,8 +123,6 @@ class _TreemapState extends State<Treemap> {
           }
         }
         return pivotIndex;
-      default:
-        return -1;
     }
   }
 

packages/devtools_app/lib/src/shared/primitives/utils.dart

@@ -518,7 +518,6 @@ class TimeRange {
       case TimeUnit.microseconds:
         return '[${_start?.inMicroseconds} μs - ${end?.inMicroseconds} μs]';
       case TimeUnit.milliseconds:
-      default:
         return '[${_start?.inMilliseconds} ms - ${end?.inMilliseconds} ms]';
     }
   }

packages/devtools_app/lib/src/shared/table/_table_row.dart

@@ -365,7 +365,6 @@ class _TableRowState<T> extends State<TableRow<T>>
       case ColumnAlignment.right:
         return Alignment.centerRight;
       case ColumnAlignment.left:
-      default:
         return Alignment.centerLeft;
     }
   }

packages/devtools_app/lib/src/shared/table/table_data.dart

@@ -175,7 +175,6 @@ extension ColumnDataExtension<T> on ColumnData<T> {
       case ColumnAlignment.right:
         return MainAxisAlignment.end;
       case ColumnAlignment.left:
-      default:
         return MainAxisAlignment.start;
     }
   }
@@ -187,7 +186,6 @@ extension ColumnDataExtension<T> on ColumnData<T> {
       case ColumnAlignment.right:
         return TextAlign.right;
       case ColumnAlignment.left:
-      default:
         return TextAlign.left;
     }
   }