[dart2js] Replace accesses to options.nullSafetyMode with

`options.useLegacySubtyping` where possible.

Change-Id: I462044e536f061cc0c67b044b986494801f58e1b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150765
Reviewed-by: Sigmund Cherem <[email protected]>
Commit-Queue: Mayank Patke <[email protected]>

Author: fishythefish

pkg/compiler/lib/src/js_model/element_map_impl.dart

@@ -1184,9 +1184,9 @@ class JsKernelToElementMap implements JsToElementMap, IrToElementMap {
         environment: _environment.toMap(),
         enableTripleShift:
             options.languageExperiments[ir.ExperimentalFlag.tripleShift],
-        evaluationMode: options.nullSafetyMode == NullSafetyMode.sound
-            ? ir.EvaluationMode.strong
-            : ir.EvaluationMode.weak);
+        evaluationMode: options.useLegacySubtyping
+            ? ir.EvaluationMode.weak
+            : ir.EvaluationMode.strong);
   }
 
   @override

pkg/compiler/lib/src/kernel/element_map_impl.dart

@@ -818,9 +818,9 @@ class KernelToElementMapImpl implements KernelToElementMap, IrToElementMap {
         environment: _environment.toMap(),
         enableTripleShift:
             options.languageExperiments[ir.ExperimentalFlag.tripleShift],
-        evaluationMode: options.nullSafetyMode == NullSafetyMode.sound
-            ? ir.EvaluationMode.strong
-            : ir.EvaluationMode.weak);
+        evaluationMode: options.useLegacySubtyping
+            ? ir.EvaluationMode.weak
+            : ir.EvaluationMode.strong);
   }
 
   @override

pkg/compiler/lib/src/kernel/loader.dart

@@ -64,7 +64,7 @@ class KernelLoaderTask extends CompilerTask {
       // We defer selecting the platform until we've resolved the NNBD mode.
       String getPlatformFilename() {
         String platform = targetName;
-        if ((_options.nullSafetyMode == NullSafetyMode.sound)) {
+        if (!_options.useLegacySubtyping) {
           platform += "_nnbd_strong";
         }
         platform += "_platform.dill";

pkg/compiler/lib/src/options.dart

@@ -350,6 +350,9 @@ class CompilerOptions implements DiagnosticOptions {
   /// unsound or sound semantics.
   ///
   /// If unspecified, the mode must be inferred from the entrypoint.
+  ///
+  /// This option should rarely need to be accessed directly. Consider using
+  /// [useLegacySubtyping] instead.
   NullSafetyMode nullSafetyMode = NullSafetyMode.unspecified;
   bool _soundNullSafety = false;
   bool _noSoundNullSafety = false;

pkg/compiler/test/model/cfe_constant_evaluation_test.dart

@@ -20,7 +20,6 @@ import 'package:compiler/src/ir/constants.dart';
 import 'package:compiler/src/ir/visitors.dart';
 import 'package:compiler/src/kernel/kernel_strategy.dart';
 import 'package:compiler/src/kernel/element_map_impl.dart';
-import 'package:compiler/src/options.dart';
 import 'package:front_end/src/api_prototype/constant_evaluator.dart' as ir;
 import 'package:front_end/src/api_unstable/dart2js.dart' as ir;
 import 'package:kernel/ast.dart' as ir;
@@ -691,10 +690,9 @@ Future testData(TestData data) async {
           },
                   environment: environment,
                   supportReevaluationForTesting: true,
-                  evaluationMode:
-                      compiler.options.nullSafetyMode == NullSafetyMode.sound
-                          ? ir.EvaluationMode.strong
-                          : ir.EvaluationMode.weak);
+                  evaluationMode: compiler.options.useLegacySubtyping
+                      ? ir.EvaluationMode.weak
+                      : ir.EvaluationMode.strong);
           ir.Constant evaluatedConstant = evaluator.evaluate(
               new ir.StaticTypeContext(node, typeEnvironment), initializer);