Stable naming of interceptors

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

 // Copyright (c) 2011, 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;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 521 matching lines @@
   }
 
   String getInterceptorName(Element element, Collection<ClassElement> classes) {
     if (classes.contains(compiler.objectClass)) {
       // If the object class is in the set of intercepted classes, we
       // need to go through the generic getInterceptorMethod.
       return getName(element);
     }
     // Use the unminified names here to construct the interceptor names.  This
     // helps ensure that they don't all suddenly change names due to a name
-    // clash in the minifier, which would affect the diff size.
+    // clash in the minifier, which would affect the diff size.  Sort the names
+    // of the classes to ensure name is stable and predicatble for the suggested
+    // names.
     StringBuffer buffer = new StringBuffer('${element.name.slowToString()}\$');
-    for (ClassElement cls in classes) {
-      buffer.add(cls.name.slowToString());
-    }
+    List<String> names = classes.map((cls) => cls.name.slowToString()).toList();
+    names.sort();
+    names.forEach(buffer.add);
     return getMappedGlobalName(buffer.toString());
   }
 
   String getBailoutName(Element element) {
     String name = bailoutNames[element];
     if (name != null) return name;
     bool global = !element.isInstanceMember();
     // Despite the name of the variable, this gets the minified name when we
     // are minifying, but it doesn't really make much difference.  The
     // important thing is that it is a unique name.  We add $bailout and, if we
@@ skipping 194 matching lines @@
       return const SourceString(r'$or');
     } else if (value == '-') {
       return const SourceString(r'$sub');
     } else if (value == 'unary-') {
       return const SourceString(r'$negate');
     } else {
       return name;
     }
   }
 }