update parser to use token.isModifier

Change-Id: Iee07cbde6c45b621bb13d1774c1d9f4bd97268ea
Reviewed-on: https://dart-review.googlesource.com/6840
Reviewed-by: Peter von der Ahé <ahe@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Dan Rubel <danrubel@google.com>

pkg/front_end/lib/src/fasta/parser/parser.dart

@@ -2048,8 +2048,6 @@ class Parser {
     return expect(';', token);
   }
 
-  bool isModifier(Token token) => modifierOrder(token) < 127;
-
   /// Provides a partial order on modifiers.
   ///
   /// The order is based on the order modifiers must appear in according to the
@@ -2075,7 +2073,7 @@ class Parser {
   }
 
   Token parseModifier(Token token) {
-    assert(isModifier(token));
+    assert(token.isModifier);
     listener.handleModifier(token);
     return token.next;
   }
@@ -2496,7 +2494,7 @@ class Parser {
     Token start = token;
     bool isExternal = false;
     int modifierCount = 0;
-    while (isModifier(token)) {
+    while (token.isModifier) {
       if (optional('external', token)) {
         isExternal = true;
       }
@@ -2911,7 +2909,7 @@ class Parser {
 
   Token parseExpressionStatementOrConstDeclaration(Token token) {
     assert(optional('const', token));
-    if (isModifier(token.next)) {
+    if (token.next.isModifier) {
       return parseVariablesDeclaration(token);
     } else {
       return parseType(

pkg/front_end/lib/src/scanner/token.dart

@@ -185,7 +185,7 @@ class Keyword extends TokenType {
   static const Keyword EXTENDS = const Keyword("extends", "EXTENDS");
 
   static const Keyword EXTERNAL =
-      const Keyword("external", "EXTERNAL", isBuiltIn: true);
+      const Keyword("external", "EXTERNAL", isBuiltIn: true, isModifier: true);
 
   static const Keyword FACTORY =
       const Keyword("factory", "FACTORY", isBuiltIn: true);
@@ -272,7 +272,7 @@ class Keyword extends TokenType {
   static const Keyword TYPEDEF = const Keyword("typedef", "TYPEDEF",
       isBuiltIn: true, isTopLevelKeyword: true);
 
-  static const Keyword VAR = const Keyword("var", "VAR");
+  static const Keyword VAR = const Keyword("var", "VAR", isModifier: true);
 
   static const Keyword VOID = const Keyword("void", "VOID");
 

pkg/front_end/test/token_test.dart

@@ -177,8 +177,10 @@ class Foo {
       Keyword.ABSTRACT,
       Keyword.CONST,
       Keyword.COVARIANT,
+      Keyword.EXTERNAL,
       Keyword.FINAL,
       Keyword.STATIC,
+      Keyword.VAR,
     ]);
     for (Keyword keyword in Keyword.values) {
       var isModifier = modifierKeywords.contains(keyword);