Break up another large file

pkg/analyzer/lib/src/generated/type_system.dart

Index: pkg/analyzer/lib/src/generated/type_system.dart
diff --git a/pkg/analyzer/lib/src/generated/type_system.dart b/pkg/analyzer/lib/src/generated/type_system.dart
index 8826bfb02568bd647c9c5baff5ad75194d40f19b..d4860c23974a0924eb5ea838b12376513109c945 100644
--- a/pkg/analyzer/lib/src/generated/type_system.dart
+++ b/pkg/analyzer/lib/src/generated/type_system.dart
@@ -11,12 +11,12 @@ import 'package:analyzer/dart/ast/ast.dart' show AstNode;
 import 'package:analyzer/dart/ast/token.dart' show TokenType;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/error/listener.dart' show ErrorReporter;
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/error/codes.dart' show StrongModeCode;
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptionsImpl;
-import 'package:analyzer/src/generated/error.dart'
-    show ErrorReporter, StrongModeCode;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/generated/utilities_dart.dart' show ParameterKind;
 import 'package:analyzer/src/generated/utilities_general.dart'
@@ -566,6 +566,21 @@ class StrongTypeSystemImpl extends TypeSystem {
         !nonnullableTypes.contains(_getTypeFullyQualifiedName(type));
   }
 
+  /// Check that [f1] is a subtype of [f2] for an override.
+  ///
+  /// This is different from the normal function subtyping in two ways:
+  /// - we know the function types are strict arrows,
+  /// - it allows opt-in covariant parameters.
+  bool isOverrideSubtypeOf(FunctionType f1, FunctionType f2) {
+    return FunctionTypeImpl.relate(
+        f1,
+        f2,
+        (t1, t2, t1Covariant, _) =>
+            isSubtypeOf(t2, t1) || t1Covariant && isSubtypeOf(t1, t2),
+        instantiateToBounds,
+        returnRelation: isSubtypeOf);
+  }
+
   @override
   bool isSubtypeOf(DartType leftType, DartType rightType) {
     return _isSubtypeOf(leftType, rightType, null);
@@ -824,21 +839,6 @@ class StrongTypeSystemImpl extends TypeSystem {
         returnRelation: isSubtypeOf);
   }
 
-  /// Check that [f1] is a subtype of [f2] for an override.
-  ///
-  /// This is different from the normal function subtyping in two ways:
-  /// - we know the function types are strict arrows,
-  /// - it allows opt-in covariant parameters.
-  bool isOverrideSubtypeOf(FunctionType f1, FunctionType f2) {
-    return FunctionTypeImpl.relate(
-        f1,
-        f2,
-        (t1, t2, t1Covariant, _) =>
-            isSubtypeOf(t2, t1) || t1Covariant && isSubtypeOf(t1, t2),
-        instantiateToBounds,
-        returnRelation: isSubtypeOf);
-  }
-
   bool _isInterfaceSubtypeOf(
       InterfaceType i1, InterfaceType i2, Set<Element> visited) {
     // Guard recursive calls