Do not emit semicolons for await expressions in ToSourceVisitor

pkg/analyzer/lib/src/generated/ast.dart

 // Copyright (c) 2014, 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 engine.ast;
 
 import 'dart:collection';
 
 import 'element.dart';
 import 'engine.dart' show AnalysisEngine;
@@ skipping 18033 matching lines @@
     _writer.print(node.operator.lexeme);
     _writer.print(' ');
     _visitNode(node.rightHandSide);
     return null;
   }
 
   @override
   Object visitAwaitExpression(AwaitExpression node) {
     _writer.print("await ");
     _visitNode(node.expression);
-    _writer.print(";");
     return null;
   }
 
   @override
   Object visitBinaryExpression(BinaryExpression node) {
     _visitNode(node.leftOperand);
     _writer.print(' ');
     _writer.print(node.operator.lexeme);
     _writer.print(' ');
     _visitNode(node.rightOperand);
@@ skipping 2582 matching lines @@
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_expression, visitor);
   }
 }