Remove unused constructor, fixed two spelling errors (#14)

lib/src/utf32.dart

diff --git a/lib/src/utf32.dart b/lib/src/utf32.dart
index 08917db..8cb2870 100644
--- a/lib/src/utf32.dart
+++ b/lib/src/utf32.dart
@@ -184,7 +184,7 @@
   Utf32BytesDecoder get iterator => codeunitsProvider();
 }
 
-/// Abstrace parent class converts encoded bytes to codepoints.
+/// Abstract parent class converts encoded bytes to codepoints.
 abstract class Utf32BytesDecoder implements ListRangeIterator {
   // TODO(kevmoo): should this field be private?
   final ListRangeIterator utf32EncodedBytesIterator;

lib/src/utf8.dart

diff --git a/lib/src/utf8.dart b/lib/src/utf8.dart
index 5cbc23c..778c865 100644
--- a/lib/src/utf8.dart
+++ b/lib/src/utf8.dart
@@ -164,11 +164,7 @@
       : utf8EncodedBytesIterator =
             (ListRange(utf8EncodedBytes, offset, length)).iterator;
 
-  Utf8Decoder._fromListRangeIterator(ListRange source,
-      [this.replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT])
-      : utf8EncodedBytesIterator = source.iterator;
-
-  // Decode the remaininder of the characters in this decoder
+  // Decode the remainder of the characters in this decoder
   //into a [List<int>].
   List<int> decodeRest() {
     var codepoints = List<int>(utf8EncodedBytesIterator.remaining);