allow await to be any value, fixes part of #264

lib/src/checker/checker.dart

 // Copyright (c) 2015, 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 dev_compiler.src.checker.checker;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/scanner.dart' show Token, TokenType;
@@ skipping 652 matching lines @@
     node.visitChildren(this);
   }
 
   @override
   void visitYieldStatement(YieldStatement node) {
     _checkReturnOrYield(node.expression, node, node.star != null);
     node.visitChildren(this);
   }
 
   @override
-  void visitAwaitExpression(AwaitExpression node) {
-    checkAssignment(node.expression, rules.provider.futureDynamicType);
-    node.visitChildren(this);
-  }
-
-  @override
   void visitPropertyAccess(PropertyAccess node) {
     var target = node.realTarget;
     if (rules.isDynamicTarget(target)) {
       _recordDynamicInvoke(node, target);
     }
     node.visitChildren(this);
   }
 
   @override
   void visitPrefixedIdentifier(PrefixedIdentifier node) {
@@ skipping 314 matching lines @@
     if (info is CoercionInfo) {
       // TODO(jmesserly): if we're run again on the same AST, we'll produce the
       // same annotations. This should be harmless. This might go away once
       // CodeChecker is integrated better with analyzer, as it will know that
       // checking has already been performed.
       // assert(CoercionInfo.get(info.node) == null);
       CoercionInfo.set(info.node, info);
     }
   }
 }