Async/await/yield[*] support for dart_fmt

pkg/analyzer/lib/src/services/formatter_impl.dart

 // Copyright (c) 2013, 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 formatter_impl;
 
 import 'dart:math';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/parser.dart';
@@ skipping 489 matching lines @@
     if (!node.statements.isEmpty) {
       visitNodes(node.statements, precededBy: newlines, separatedBy: newlines);
       newlines();
     } else {
       preserveLeadingNewlines();
     }
     token(node.rightBracket, precededBy: unindent);
   }
 
   visitBlockFunctionBody(BlockFunctionBody node) {
-    token(node.keyword, followedBy: nonBreakingSpace);
+    // sync[*] or async[*]
+    token(node.keyword);
+    token(node.star);
+    if (node.keyword != null) {
+      nonBreakingSpace();
+    }
+
     visit(node.block);
   }
 
   visitBooleanLiteral(BooleanLiteral node) {
     token(node.literal);
   }
 
   visitBreakStatement(BreakStatement node) {
     token(node.keyword);
     visitNode(node.label, precededBy: space);
@@ skipping 308 matching lines @@
   visitFieldFormalParameter(FieldFormalParameter node) {
     token(node.keyword, followedBy: space);
     visitNode(node.type, followedBy: space);
     token(node.thisToken);
     token(node.period);
     visit(node.identifier);
     visit(node.parameters);
   }
 
   visitForEachStatement(ForEachStatement node) {
+    token(node.awaitKeyword, followedBy: nonBreakingSpace);
     token(node.forKeyword);
     space();
     token(node.leftParenthesis);
     if (node.loopVariable != null) {
       visit(node.loopVariable);
     } else {
       visit(node.identifier);
     }
     space();
     token(node.inKeyword);
@@ skipping 1004 matching lines @@
   int linesBetween(int lastOffset, int currentOffset) {
     var lastLine =
         lineInfo.getLocation(lastOffset).lineNumber;
     var currentLine =
         lineInfo.getLocation(currentOffset).lineNumber;
     return currentLine - lastLine;
   }
 
   String toString() => writer.toString();
 }