dart2js: Forbid # placeholders in JS function bodies.

pkg/compiler/lib/src/ssa/builder.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.
 
 part of ssa;
 
 class SsaFunctionCompiler implements FunctionCompiler {
   final SsaCodeGeneratorTask generator;
   final SsaBuilderTask builder;
   final SsaOptimizerTask optimizer;
@@ skipping 4136 matching lines @@
     if (nativeBehavior.codeTemplate.positionalArgumentCount != inputs.length) {
       reporter.reportErrorMessage(
           node, MessageKind.GENERIC,
           {'text':
             'Mismatch between number of placeholders'
             ' and number of arguments.'});
       stack.add(graph.addConstantNull(compiler));  // Result expected on stack.
       return;
     }
 
+    if (native.HasCapturedPlaceholders.check(nativeBehavior.codeTemplate.ast)) {
+      reporter.reportErrorMessage(node, MessageKind.JS_PLACEHOLDER_CAPTURE);
+    }
+
     TypeMask ssaType =
         TypeMaskFactory.fromNativeBehavior(nativeBehavior, compiler);
 
     SourceInformation sourceInformation =
         sourceInformationBuilder.buildCall(node, node.argumentsNode);
     if (nativeBehavior.codeTemplate.isExpression) {
       push(new HForeignCode(
           nativeBehavior.codeTemplate, ssaType, inputs,
           effects: nativeBehavior.sideEffects,
           nativeBehavior: nativeBehavior)
@@ skipping 4990 matching lines @@
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaBuilder builder) {
     JavaScriptBackend backend = builder.compiler.backend;
     ClassElement cls = backend.helpers.DynamicRuntimeType;
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, classWorld)));
   }
 }