Revert "Add optional message to assert in Dart2js - continued"

pkg/compiler/lib/src/tree/nodes.dart

Index: pkg/compiler/lib/src/tree/nodes.dart
diff --git a/pkg/compiler/lib/src/tree/nodes.dart b/pkg/compiler/lib/src/tree/nodes.dart
index 7ef28dcb7764aeaf3647454e861978f1e42e0a87..6c4516b416efd886b4e4afb3fa48870660a0b5f5 100644
--- a/pkg/compiler/lib/src/tree/nodes.dart
+++ b/pkg/compiler/lib/src/tree/nodes.dart
@@ -9,7 +9,6 @@ abstract class Visitor<R> {
 
   R visitNode(Node node);
 
-  R visitAssert(Assert node) => visitStatement(node);
   R visitAsyncForIn(AsyncForIn node) => visitLoop(node);
   R visitAsyncModifier(AsyncModifier node) => visitNode(node);
   R visitAwait(Await node) => visitExpression(node);
@@ -147,7 +146,6 @@ abstract class Node extends NullTreeElementMixin implements Spannable {
 
   Token getEndToken();
 
-  Assert asAssert() => null;
   AsyncModifier asAsyncModifier() => null;
   Await asAwait() => null;
   Block asBlock() => null;
@@ -1213,30 +1211,6 @@ class Await extends Expression {
   Token getEndToken() => expression.getEndToken();
 }
 
-class Assert extends Statement {
-  final Token assertToken;
-  final Expression condition;
-  /** Message may be `null`. */
-  final Expression message;
-  final Token semicolonToken;
-
-  Assert(this.assertToken, this.condition, this.message, this.semicolonToken);
-
-  Assert asAssert() => this;
-
-  bool get hasMessage => message != null;
-
-  accept(Visitor visitor) => visitor.visitAssert(this);
-
-  visitChildren(Visitor visitor) {
-    condition.accept(visitor);
-    if (message != null) message.accept(visitor);
-  }
-
-  Token getBeginToken() => assertToken;
-  Token getEndToken() => semicolonToken;
-}
-
 class Rethrow extends Statement {
   final Token throwToken;
   final Token endToken;