Avoid generating VariableUse nodes with non-identifier names

sdk/lib/_internal/compiler/implementation/js_backend/backend.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_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1753 matching lines @@
   }
 
   jsAst.Call generateIsJsIndexableCall(jsAst.Expression use1,
                                        jsAst.Expression use2) {
     String dispatchPropertyName = 'init.dispatchPropertyName';
 
     // We pass the dispatch property record to the isJsIndexable
     // helper rather than reading it inside the helper to increase the
     // chance of making the dispatch record access monomorphic.
     jsAst.PropertyAccess record = new jsAst.PropertyAccess(
-        use2, new jsAst.VariableUse(dispatchPropertyName));
+        use2, js(dispatchPropertyName));
 
     List<jsAst.Expression> arguments = <jsAst.Expression>[use1, record];
-    FunctionElement helper =
-        compiler.findHelper('isJsIndexable');
-    String helperName = namer.isolateAccess(helper);
-    return new jsAst.Call(new jsAst.VariableUse(helperName), arguments);
+    FunctionElement helper = compiler.findHelper('isJsIndexable');
+    jsAst.Expression helperExpression = namer.elementAccess(helper);
+    return new jsAst.Call(helperExpression, arguments);
   }
 
   bool isTypedArray(TypeMask mask) {
     // Just checking for [:TypedData:] is not sufficient, as it is an
     // abstract class any user-defined class can implement. So we also
     // check for the interface [JavaScriptIndexingBehavior].
     return compiler.typedDataClass != null
         && mask.satisfies(compiler.typedDataClass, compiler)
         && mask.satisfies(jsIndexingBehaviorInterface, compiler);
   }
@@ skipping 124 matching lines @@
   }
 }
 
 /// Records that [constant] is used by [user.element].
 class Dependency {
   final Constant constant;
   final TreeElements user;
 
   const Dependency(this.constant, this.user);
 }