Remove workarounds for dart-lang/language#1785.

PiperOrigin-RevId: 415311843

Author: stereotype441

charts_common/lib/src/chart/bar/base_bar_renderer.dart

@@ -398,10 +398,7 @@ abstract class BaseBarRenderer<D, R extends BaseBarRendererElement,
         final domainValue = domainFn(barIndex);
 
         final measureValue = measureFn(barIndex);
-        // TODO: remove this explicit `bool` type when no longer
-        // needed to work around
-        // https://github.com/dart-lang/language/issues/1785
-        final bool measureIsNull = measureValue == null;
+        final measureIsNull = measureValue == null;
         final measureIsNegative = !measureIsNull && measureValue < 0;
 
         // Each bar should be stored in barStackMap in a structure that mirrors

charts_common/lib/src/chart/common/behavior/selection/select_nearest.dart

@@ -245,9 +245,7 @@ class SelectNearest<D> implements ChartBehavior<D> {
       final domainFn = series.domainFn;
       final domainLowerBoundFn = series.domainLowerBoundFn;
       final domainUpperBoundFn = series.domainUpperBoundFn;
-      // TODO: remove this explicit `bool` type when no longer
-      // needed to work around https://github.com/dart-lang/language/issues/1785
-      final bool testBounds =
+      final testBounds =
           domainLowerBoundFn != null && domainUpperBoundFn != null;
 
       for (var i = 0; i < series.data.length; i++) {

charts_common/pubspec.yaml

@@ -4,7 +4,7 @@ description: A common library for charting packages.
 homepage: https://github.com/google/charts
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
+  sdk: '>=2.15.0 <3.0.0'
 
 dependencies:
   collection: ^1.14.5