Use failedAt in more places

pkg/compiler/lib/src/js/js.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 js;
 
 import 'package:js_ast/js_ast.dart';
 
 import '../common.dart';
 import '../options.dart';
@@ skipping 47 matching lines @@
 class Dart2JSJavaScriptPrintingContext implements JavaScriptPrintingContext {
   final DumpInfoTask monitor;
   final CodeBuffer outBuffer;
   final CodePositionListener codePositionListener;
 
   Dart2JSJavaScriptPrintingContext(
       this.monitor, this.outBuffer, this.codePositionListener);
 
   @override
   void error(String message) {
-    throw new SpannableAssertionFailure(NO_LOCATION_SPANNABLE, message);
+    failedAt(NO_LOCATION_SPANNABLE, message);
   }
 
   @override
   void emit(String string) {
     outBuffer.add(string);
   }
 
   @override
   void enterNode(Node node, int startPosition) {
     codePositionListener.onStartPosition(node, startPosition);
@@ skipping 109 matching lines @@
   }
   if (node is PropertyAccess) {
     PropertyAccess access = node;
     if (access.receiver is InterpolatedExpression) {
       InterpolatedExpression hole = access.receiver;
       return hole.isPositional && hole.nameOrPosition == 0;
     }
   }
   return false;
 }