dart2js cps: Remove NonTailThrow.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
index 73e4cfe22a5cae37752810daffd7ea7ddb4ece2b..345da913cb70b6c80db3fd49c6e79dffdc77b435 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
@@ -386,10 +386,6 @@ class Builder implements cps_ir.Visitor<Node> {
     return new Unreachable();
   }
 
-  Expression visitNonTailThrow(cps_ir.NonTailThrow node) {
-    return unexpectedNode(node);
-  }
-
   Statement continueWithExpression(cps_ir.Reference continuation,
                                    Expression expression) {
     cps_ir.Continuation cont = continuation.definition;