analyzer: Remove new and unused strictCasts field from LinterContextImpl

Change-Id: I97ada794a8ea7c1c2b72bdaece2d4e5825d28de9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/344200
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Phil Quitslund <pquitslund@google.com>

pkg/analyzer/lib/src/lint/linter.dart

@@ -32,11 +32,7 @@ import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
 import 'package:analyzer/src/dart/element/type_system.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart'
- show
- AnalysisErrorInfo,
- AnalysisErrorInfoImpl,
- AnalysisOptions,
- AnalysisOptionsImpl;
+ show AnalysisErrorInfo, AnalysisErrorInfoImpl, AnalysisOptions;
 import 'package:analyzer/src/generated/resolver.dart' show ScopeResolverVisitor;
 import 'package:analyzer/src/lint/analysis.dart';
 import 'package:analyzer/src/lint/io.dart';
@@ -314,11 +310,6 @@ class LinterContextImpl implements LinterContext {
  '`currentUnit.unit.declaredElement?.session`.')
  DeclaredVariables get declaredVariables => _declaredVariables;
 
- bool get strictCasts =>
- // TODO(pq): update when there's a better API to access strictCasts.
- // ignore: deprecated_member_use_from_same_package
- (analysisOptions as AnalysisOptionsImpl).strictCasts;
-
  @override
  bool canBeConst(Expression expression) {
  if (expression is InstanceCreationExpressionImpl) {