Handle const constructor invocation in kernel_impact.

pkg/compiler/lib/src/util/util.dart

 // Copyright (c) 2011, 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.
 
 library dart2js.util;
 
 import 'characters.dart';
 import 'util_implementation.dart';
 
 export 'emptyset.dart';
@@ skipping 24 matching lines @@
     int high = existing >> 15;
     int low = existing & 0x7fff;
     return ((high * 13) ^ (low * 997) ^ h) & SMI_MASK;
   }
 
   /// Mix the bits of `object.hashCode` with [existing].
   static int objectHash(Object object, [int existing = 0]) {
     return mixHashCodeBits(existing, object.hashCode);
   }
 
+  /// Mix the bits of `.hashCode` all non-null objects.
+  static int objectsHash(Object obj1, [Object obj2, Object obj3]) {
+    int hash = 0;
+    if (obj3 != null) hash = objectHash(obj3, hash);
+    if (obj2 != null) hash = objectHash(obj2, hash);
+    return objectHash(obj1, hash);
+  }
+
   /// Mix the bits of the element hash codes of [list] with [existing].
   static int listHash(List list, [int existing = 0]) {
     int h = existing;
     int length = list.length;
     for (int i = 0; i < length; i++) {
       h = mixHashCodeBits(h, list[i].hashCode);
     }
     return h;
   }
 
@@ skipping 178 matching lines @@
   if (usedNames.contains(suggestedName)) {
     int counter = 0;
     while (usedNames.contains(result)) {
       counter++;
       result = "$suggestedName$counter";
     }
   }
   usedNames.add(result);
   return result;
 }