Add optional message to assert in Dart2js.

pkg/compiler/lib/src/resolution/semantic_visitor.dart

 // Copyright (c) 2015, 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.semantics_visitor;
 
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../diagnostics/spannable.dart' show
     Spannable,
@@ skipping 1279 matching lines @@
   /// For instance:
   ///
   ///     m() { dynamic = rhs; }
   ///
   R visitDynamicTypeLiteralSet(
       SendSet node,
       ConstantExpression constant,
       Node rhs,
       A arg);
 
-  /// Call to `assert` with [expression] as the condition.
-  ///
-  /// For instance:
-  ///
-  ///     m() { assert(expression); }
-  ///
-  R visitAssert(
-      Send node,
-      Node expression,
-      A arg);
-
-  /// Call to `assert` with the wrong number of [arguments].
-  ///
-  /// For instance:
-  ///
-  ///     m() { assert(); }
-  ///
-  /// or
-  ///
-  ///     m() { assert(expression1, expression2); }
-  ///
-  R errorInvalidAssert(
-      Send node,
-      NodeList arguments,
-      A arg);
-
   /// Binary expression `left operator right` where [operator] is a user
   /// definable operator. Binary expressions using operator `==` are handled
   /// by [visitEquals] and index operations `a[b]` are handled by [visitIndex].
   ///
   /// For instance:
   ///
   ///     add(a, b) => a + b;
   ///     sub(a, b) => a - b;
   ///     mul(a, b) => a * b;
   ///
@@ skipping 3819 matching lines @@
   ///       C() : this._(42);
   ///     }
   ///
   R errorUnresolvedThisConstructorInvoke(
       Send node,
       Element element,
       NodeList arguments,
       Selector selector,
       A arg);
 }