Handle const constructor invocation in kernel_impact.

pkg/compiler/lib/src/js_backend/kernel_task.dart

 // Copyright (c) 2016, 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.
 
 import '../compiler.dart';
 import '../common/names.dart';
 import '../elements/elements.dart';
 import '../kernel/kernel.dart';
 import 'package:kernel/ast.dart' as ir;
 
@@ skipping 18 matching lines @@
   void buildKernelIr() {
     program = buildProgram(_compiler.mainApp);
   }
 
   /// Builds the kernel IR program for the main function exported from
   /// [library].
   ///
   /// May enqueue more elements to the resolution queue.
   ir.Program buildProgram(LibraryElement library) {
     return new ir.Program(kernel.libraryDependencies(library.canonicalUri))
-      ..mainMethod = kernel.functionToIr(
-          library.findExported(Identifiers.main));
+      ..mainMethod =
+          kernel.functionToIr(library.findExported(Identifiers.main));
   }
 }