Avoid generating VariableUse nodes with non-identifier names

sdk/lib/_internal/compiler/implementation/js/nodes.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 js;
 
 abstract class NodeVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 781 matching lines @@
     argument.accept(visitor);
   }
 
 
   int get precedenceLevel => UNARY;
 }
 
 abstract class VariableReference extends Expression {
   final String name;
 
-  // We treat operators as if they were special functions. They can thus be
-  // referenced like other variables.
-  VariableReference(this.name);
+  VariableReference(this.name) {
+    assert(_identifierRE.hasMatch(name));
+  }
+  static RegExp _identifierRE = new RegExp(r'^[A-Za-z_$][A-Za-z_$0-9]*$');
 
   accept(NodeVisitor visitor);
   int get precedenceLevel => PRIMARY;
   void visitChildren(NodeVisitor visitor) {}
 }
 
 class VariableUse extends VariableReference {
   VariableUse(String name) : super(name);
 
   accept(NodeVisitor visitor) => visitor.visitVariableUse(this);
   VariableUse _clone() => new VariableUse(name);
 
   VariableUse asVariableUse() => this;
 
   toString() => 'VariableUse($name)';
 }
 
 class VariableDeclaration extends VariableReference {
   VariableDeclaration(String name) : super(name);
 
   accept(NodeVisitor visitor) => visitor.visitVariableDeclaration(this);
   VariableDeclaration _clone() => new VariableDeclaration(name);
 }
 
 class Parameter extends VariableDeclaration {
-  Parameter(String id) : super(id);
+  Parameter(String name) : super(name);
 
   accept(NodeVisitor visitor) => visitor.visitParameter(this);
   Parameter _clone() => new Parameter(name);
 }
 
 class This extends Parameter {
   This() : super("this");
 
   accept(NodeVisitor visitor) => visitor.visitThis(this);
   This _clone() => new This();
@@ skipping 282 matching lines @@
 class Comment extends Statement {
   final String comment;
 
   Comment(this.comment);
 
   accept(NodeVisitor visitor) => visitor.visitComment(this);
   Comment _clone() => new Comment(comment);
 
   void visitChildren(NodeVisitor visitor) {}
 }