Set 'isSyntheticDefault' for default constructors.

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

 library;
 import self as self;
 import "dart:core" as core;
 
 class Uninitialized extends core::Object {
   field core::int x;
-  constructor •() → void
+  default constructor •() → void

[Johnni Winther, 2017/07/14 09:22:02]

Why isn't this change also in the .direct.expect file?

[ahe, 2017/07/14 09:42:26]

Same explanation.

     ;
 }
 class PartiallyInitialized extends core::Object {
   field core::int x;
   constructor •(core::int x) → void
     ;
   constructor noInitializer() → void
     ;
 }
 class Initialized extends core::Object {
   field core::int x;
   constructor •(core::int x) → void
     ;
 }
 class Forwarding extends core::Object {
   field core::int x;
   constructor initialize(core::int x) → void
     ;
   constructor •(core::int arg) → void
     ;
 }
 static field core::int uninitializedTopLevel;
 static field core::int initializedTopLevel;
 static method main() → dynamic
   ;