Use failedAt in more places

pkg/compiler/lib/src/closure.dart

 // Copyright (c) 2012, 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 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show ParsingContext, Resolution;
 import 'common/tasks.dart' show CompilerTask, Measurer;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'constants/expressions.dart';
@@ skipping 387 matching lines @@
 
   @override
   Local get declaredEntity => local;
 
   @override
   Entity get rootOfScope => closureClass;
 
   bool get hasNode => false;
 
   VariableDefinitions get node {
-    throw new SpannableAssertionFailure(
-        local, 'Should not access node of ClosureFieldElement.');
+    throw failedAt(local, 'Should not access node of ClosureFieldElement.');
   }
 
   bool get hasResolvedAst => hasTreeElements;
 
   ResolvedAst get resolvedAst {
     return new ParsedResolvedAst(this, null, null, treeElements,
         memberContext.compilationUnit.script.resourceUri);
   }
 
   Expression get initializer {
-    throw new SpannableAssertionFailure(
+    throw failedAt(
         local, 'Should not access initializer of ClosureFieldElement.');
   }
 
   bool get isInstanceMember => true;
   bool get isAssignable => false;
 
   ResolutionDartType computeType(Resolution resolution) => type;
 
   ResolutionDartType get type {
     if (local is LocalElement) {
@@ skipping 1109 matching lines @@
 ///
 /// Move the below classes to a JS model eventually.
 ///
 abstract class JSEntity implements MemberEntity {
   Local get declaredEntity;
 }
 
 abstract class PrivatelyNamedJSEntity implements JSEntity {
   Entity get rootOfScope;
 }