Remove unused API.

dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart

Index: dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart b/dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart
index d44702926837a2f349dc2d795967d81648c967c3..013e11c84b56d5be29e62689c85a07847bb9a250 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/scanner/keyword.dart
@@ -103,7 +103,6 @@ class Keyword {
 abstract class KeywordState {
   KeywordState(this.keyword);
 
-  bool isLeaf();
   KeywordState next(int c);
   final Keyword keyword;
 
@@ -172,8 +171,6 @@ class ArrayKeywordState extends KeywordState {
   ArrayKeywordState(List<KeywordState> this.table, String syntax)
     : super((syntax == null) ? null : Keyword.keywords[syntax]);
 
-  bool isLeaf() => false;
-
   KeywordState next(int c) => table[c - $a];
 
   String toString() {
@@ -201,8 +198,6 @@ class ArrayKeywordState extends KeywordState {
 class LeafKeywordState extends KeywordState {
   LeafKeywordState(String syntax) : super(Keyword.keywords[syntax]);
 
-  bool isLeaf() => true;
-
   KeywordState next(int c) => null;
 
   String toString() => keyword.syntax;