dart2js: Refactoring, documentation, and a few bugfixes in Namer class.

pkg/compiler/lib/src/compiler.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 dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 2209 matching lines @@
       message = message();
     }
     throw new SpannableAssertionFailure(spannable, message);
   }
   return true;
 }
 
 /// Returns `true` when [s] is private if used as an identifier.
 bool isPrivateName(String s) => !s.isEmpty && s.codeUnitAt(0) == $_;
 
+/// Returns `true` when [s] is public if used as an identifier.
+bool isPublicName(String s) => !isPrivateName(s);
+
 /// A sink that drains into /dev/null.
 class NullSink implements EventSink<String> {
   final String name;
 
   NullSink(this.name);
 
   add(String value) {}
 
   void addError(Object error, [StackTrace stackTrace]) {}
 
@@ skipping 156 matching lines @@
   InterfaceType get nullType => nullClass.computeType(compiler);
 
   @override
   InterfaceType get numType => numClass.computeType(compiler);
 
   @override
   InterfaceType get stringType =>  stringClass.computeType(compiler);
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);