Fix #28740 demangle constructors in stack traces (A.A becomes new A).

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 7129 matching lines @@
         // the parent.
         fun = fun.parent_function();
       }
       result = String::Concat(Symbols::Dot(), result, Heap::kOld);
       result = String::Concat(String::Handle(fun.UserVisibleName()), result,
                               Heap::kOld);
     }
   }
   const Class& cls = Class::Handle(Owner());
   if (!cls.IsTopLevel()) {
-    result = String::Concat(Symbols::Dot(), result, Heap::kOld);
-    const String& cls_name = String::Handle(name_visibility == kScrubbedName
-                                                ? cls.ScrubbedName()
-                                                : cls.UserVisibleName());
-    result = String::Concat(cls_name, result, Heap::kOld);
+    if (kind() == RawFunction::kConstructor) {
+      result = String::Concat(Symbols::ConstructorStacktracePrefix(), result,
+                              Heap::kOld);
+    } else {
+      result = String::Concat(Symbols::Dot(), result, Heap::kOld);
+      const String& cls_name = String::Handle(name_visibility == kScrubbedName
+                                                  ? cls.ScrubbedName()
+                                                  : cls.UserVisibleName());
+      result = String::Concat(cls_name, result, Heap::kOld);
+    }
   }
   return result.raw();
 }
 
 
 RawString* Function::GetSource() const {
   if (IsImplicitConstructor() || IsSignatureFunction()) {
     // We may need to handle more cases when the restrictions on mixins are
     // relaxed. In particular we might start associating some source with the
     // forwarding constructors when it becomes possible to specify a particular
@@ skipping 15982 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart