Unify most of our utf8 implementations. This takes the implementation

lib/utf/utf32.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.
 
-#library("utf32");
-#import("unicode_core.dart");
-#import("unicode.dart");
-
 /**
  * Decodes the UTF-32 bytes as an iterable. Thus, the consumer can only convert
  * as much of the input as needed. Determines the byte order from the BOM,
  * or uses big-endian as a default. This method always strips a leading BOM.
  * Set the replacementCharacter to null to throw an IllegalArgumentException
  * rather than replace the bad value.
  */
 IterableUtf32Decoder decodeUtf32AsIterable(List<int> bytes, [
     int offset = 0, int length,
     int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
@@ skipping 167 matching lines @@
   final Function codeunitsProvider;
 
   IterableUtf32Decoder._(Function this.codeunitsProvider);
 
   Utf32BytesDecoder iterator() => codeunitsProvider();
 }
 
 /**
  * Abstrace parent class converts encoded bytes to codepoints.
  */
-class Utf32BytesDecoder implements ListRangeIterator<int> {
-  final ListRangeIterator<int> utf32EncodedBytesIterator;
+class Utf32BytesDecoder implements _ListRangeIterator<int> {
+  final _ListRangeIterator<int> utf32EncodedBytesIterator;
   final int replacementCodepoint;
 
   Utf32BytesDecoder._fromListRangeIterator(
-      ListRangeIterator<int> this.utf32EncodedBytesIterator,
+      _ListRangeIterator<int> this.utf32EncodedBytesIterator,
       int this.replacementCodepoint);
 
   factory Utf32BytesDecoder(List<int> utf32EncodedBytes, [
       int offset = 0, int length,
       int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
     if (length == null) {
       length = utf32EncodedBytes.length - offset;
     }
     if (hasUtf32beBom(utf32EncodedBytes, offset, length)) {
       return new Utf32beBytesDecoder(utf32EncodedBytes, offset + 4, length - 4,
@@ skipping 56 matching lines @@
 }
 
 /**
  * Convert UTF-32BE encoded bytes to codepoints by grouping 4 bytes
  * to produce the unicode codepoint.
  */
 class Utf32beBytesDecoder extends Utf32BytesDecoder {
   Utf32beBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0,
       int length, bool stripBom = true,
       int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      super._fromListRangeIterator((new ListRange(utf32EncodedBytes, offset,
+      super._fromListRangeIterator((new _ListRange(utf32EncodedBytes, offset,
       length)).iterator(), replacementCodepoint) {
     if (stripBom && hasUtf32beBom(utf32EncodedBytes, offset, length)) {
       skip();
     }
   }
 
   int decode() {
     int value = utf32EncodedBytesIterator.next();
     value = (value << 8) + utf32EncodedBytesIterator.next();
     value = (value << 8) + utf32EncodedBytesIterator.next();
     value = (value << 8) + utf32EncodedBytesIterator.next();
     return value;
   }
 }
 
 /**
  * Convert UTF-32BE encoded bytes to codepoints by grouping 4 bytes
  * to produce the unicode codepoint.
  */
 class Utf32leBytesDecoder extends Utf32BytesDecoder {
   Utf32leBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0,
       int length, bool stripBom = true,
       int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      super._fromListRangeIterator((new ListRange(utf32EncodedBytes, offset,
+      super._fromListRangeIterator((new _ListRange(utf32EncodedBytes, offset,
       length)).iterator(), replacementCodepoint) {
     if (stripBom && hasUtf32leBom(utf32EncodedBytes, offset, length)) {
       skip();
     }
   }
 
   int decode() {
     int value = (utf32EncodedBytesIterator.next());
     value += (utf32EncodedBytesIterator.next() << 8);
     value += (utf32EncodedBytesIterator.next() << 16);
     value += (utf32EncodedBytesIterator.next() << 24);
     return value;
   }
 }
 
 bool _validCodepoint(int codepoint) {
   return (codepoint >= 0 && codepoint < UNICODE_UTF16_RESERVED_LO) ||
       (codepoint > UNICODE_UTF16_RESERVED_HI &&
       codepoint < UNICODE_VALID_RANGE_MAX);
 }