Work around for private names in mixin applications.

lib/kernel.dart

 // Copyright (c) 2016, 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.md file.
 
 library rasta.kernel;
 
 import 'dart:async' show
     Future;
 
 import 'dart:collection' show
     Queue;
 
 import 'package:kernel/ast.dart' as ir;
 
 import 'package:kernel/checks.dart' show
     CheckParentPointers;
 
 import 'package:kernel/frontend/super_calls.dart' show
     moveSuperCallLast;
 
 import 'package:compiler/src/elements/elements.dart' show
     ClassElement,
     ConstructorElement,
     Element,
     ExportElement,
     FieldElement,
     FunctionElement,
     ImportElement,
     LibraryElement,
-    Name,
+    MixinApplicationElement,
     TypeVariableElement;
 
 import 'package:compiler/src/elements/modelx.dart' show
     ErroneousFieldElementX;
 
 import 'package:compiler/src/dart_types.dart' show
     DartType,
     FunctionType,
     InterfaceType,
     TypeKind,
@@ skipping 88 matching lines @@
     assert(() {
       libraries.forEach(checkLibrary);
       classes.forEach(checkMember);
       functions.forEach(checkMember);
       fields.forEach(checkMember);
       return true;
     });
   }
 
   ir.Name irName(String name, Element element) {
-    return new ir.Name(name, libraryToIr(element.library));
-  }
-
-  ir.Name nameToIrName(Name name) {
-    ir.Library library;
-    if (name.isPrivate) {
-      library = libraryToIr(name.library);
+    ir.Library irLibrary = null;
+    if (name.startsWith("_")) {
+      ClassElement cls = element.enclosingClass;
+      if (cls != null && cls.isMixinApplication) {
+        MixinApplicationElement mixinApplication = cls;
+        element = mixinApplication.mixin;
+      }
+      name = "${element.library.libraryOrScriptName}::$name";
+      irLibrary = libraryToIr(element.library);
     }
-    return new ir.Name(name.text, library);
+    return new ir.Name(name, irLibrary);
   }
 
   Future<ir.Library> loadLibrary(Uri uri) async {
     return libraryToIr(await compiler.libraryLoader.loadLibrary(uri));
   }
 
   ir.Library libraryToIr(LibraryElement library) {
     library = library.declaration;
     return libraries.putIfAbsent(library, () {
       String name = library.hasLibraryName ? library.libraryName : null;
@@ skipping 271 matching lines @@
     }
     field = field.declaration;
     return fields.putIfAbsent(field, () {
       compiler.analyzeElement(field);
       compiler.enqueuer.resolution.emptyDeferredTaskQueue();
       field = field.implementation;
       ir.DartType type = field.isMalformed
           ? const ir.InvalidType()
           : typeToIr(field.type);
       ir.Field fieldNode = new ir.Field(
-          nameToIrName(field.memberName), type: type, initializer: null,
+          irName(field.memberName.text, field), type: type, initializer: null,
           isFinal: field.isFinal, isStatic: field.isStatic || field.isTopLevel,
           isConst: field.isConst);
       addWork(field, () {
         setParent(fieldNode, field);
         if (!field.isMalformed && !field.isInstanceMember &&
             field.initializer != null) {
           KernelVisitor visitor =
               new KernelVisitor(field, field.treeElements, this);
           fieldNode.initializer = visitor.buildInitializer()
               ..parent = fieldNode;
@@ skipping 213 matching lines @@
 }
 
 class ConstructorTarget {
   final ConstructorElement element;
   final DartType type;
 
   ConstructorTarget(this.element, this.type);
 
   String toString() => "ConstructorTarget($element, $type)";
 }