Set 'isSyntheticDefault' for default constructors.

pkg/front_end/testcases/redirecting_factory.dart.outline.expect

 library;
 import self as self;
 import "dart:core" as core;
 
 abstract class FooBase<Tf extends core::Object> extends core::Object {
   static field dynamic _redirecting# = <dynamic>[self::FooBase::•];
   abstract get x() → core::int;
   static factory •<Tf extends core::Object>(core::int x) → self::FooBase<self::FooBase::•::Tf>
     let dynamic #redirecting_factory = self::Foo::• in invalid-expression;
 }
 abstract class Foo<T extends core::Object> extends core::Object implements self::FooBase<dynamic> {
   static field dynamic _redirecting# = <dynamic>[self::Foo::•];
   static factory •<T extends core::Object>(core::int x) → self::Foo<self::Foo::•::T>
     let dynamic #redirecting_factory = self::Bar::• in invalid-expression;
 }
 class Bar<Sb extends core::Object, Tb extends core::Object> extends core::Object implements self::Foo<self::Bar::Tb> {
   field core::int x;
   constructor •(core::int x) → void
     ;
 }
 class Builder<X extends core::Object> extends core::Object {
-  constructor •() → void
+  default constructor •() → void
     ;
   method method() → dynamic
     ;
 }
 class SimpleCase<A extends core::Object, B extends core::Object> extends core::Object {
   static field dynamic _redirecting# = <dynamic>[self::SimpleCase::•];
   static factory •<A extends core::Object, B extends core::Object>() → self::SimpleCase<self::SimpleCase::•::A, self::SimpleCase::•::B>
     let dynamic #redirecting_factory = self::SimpleCaseImpl::• in invalid-expression;
 }
 class SimpleCaseImpl<Ai extends core::Object, Bi extends core::Object> extends core::Object implements self::SimpleCase<self::SimpleCaseImpl::Ai, self::SimpleCaseImpl::Bi> {
   static field dynamic _redirecting# = <dynamic>[self::SimpleCaseImpl::•];
   static factory •<Ai extends core::Object, Bi extends core::Object>() → self::SimpleCaseImpl<self::SimpleCaseImpl::•::Ai, self::SimpleCaseImpl::•::Bi>
     let dynamic #redirecting_factory = self::SimpleCaseImpl2::• in invalid-expression;
 }
 class SimpleCaseImpl2<Ai2 extends core::Object, Bi2 extends core::Object> extends core::Object implements self::SimpleCaseImpl<self::SimpleCaseImpl2::Ai2, self::SimpleCaseImpl2::Bi2> {
-  constructor •() → void
+  default constructor •() → void
     ;
 }
 class Base<M extends core::Object> extends core::Object {
-  constructor •() → void
+  default constructor •() → void
     ;
 }
 class Mixin<M extends core::Object> extends core::Object {
-  constructor •() → void
+  default constructor •() → void
     ;
 }
 class Mix<M extends core::Object> = self::Base<self::Mix::M> with self::Mixin<self::Mix::M> {
   constructor •() → void
     : super self::Base::•()
     ;
 }
 static method main() → dynamic
   ;