Pass 'classKeyword' to endClassDeclaratio() and endNamedMixinApplication().

pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart

Index: pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart b/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
index 3310536f2688c8f64d8d722e8c7aa6f09951bb13..8017fc7432fe193460a9a961c4d915dc9beae48d 100644
--- a/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
+++ b/pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart
@@ -805,7 +805,8 @@ class AstBuilder extends ScopeListener {
 
   @override
   void endClassDeclaration(int interfacesCount, Token beginToken,
-      Token extendsKeyword, Token implementsKeyword, Token endToken) {
+      Token classKeyword, Token extendsKeyword, Token implementsKeyword,
+      Token endToken) {
     debugEvent("ClassDeclaration");
     _ClassBody body = pop();
     ImplementsClause implementsClause;
@@ -832,14 +833,6 @@ class AstBuilder extends ScopeListener {
     }
     TypeParameterList typeParameters = pop();
     SimpleIdentifier name = pop();
-    Token classKeyword;
-    // TODO(paulberry,ahe): This is a hack.  The parser should give us the class
-    // keyword.
-    if (optional('abstract', beginToken)) {
-      classKeyword = beginToken.next;
-    } else {
-      classKeyword = beginToken;
-    }
     var modifiers = pop();
     assert(modifiers == null); // TODO(paulberry)
     analyzer.Token abstractKeyword;
@@ -874,7 +867,8 @@ class AstBuilder extends ScopeListener {
 
   @override
   void endNamedMixinApplication(
-      Token beginToken, Token equalsToken, Token implementsKeyword, Token endToken) {
+      Token beginToken, Token classKeyword, Token equalsToken,
+      Token implementsKeyword, Token endToken) {
     debugEvent("NamedMixinApplication");
     ImplementsClause implementsClause;
     if (implementsKeyword != null) {
@@ -890,14 +884,6 @@ class AstBuilder extends ScopeListener {
     analyzer.Token equals = toAnalyzerToken(equalsToken);
     TypeParameterList typeParameters = pop();
     SimpleIdentifier name = pop();
-    Token classKeyword;
-    // TODO(paulberry,ahe): This is a hack.  The parser should give us the class
-    // keyword.
-    if (identical(beginToken.value, 'abstract')) {
-      classKeyword = beginToken.next;
-    } else {
-      classKeyword = beginToken;
-    }
     var modifiers = pop();
     assert(modifiers == null); // TODO(paulberry)
     analyzer.Token abstractKeyword;