Fix top level type inference for binary operators.

pkg/analyzer/test/src/summary/top_level_inference_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ skipping 1302 matching lines @@
 ''');
     checkElementText(
         library,
         r'''
 int vModuloIntInt;
 double vModuloIntDouble;
 int vMultiplyIntInt;
 double vMultiplyIntDouble;
 double vMultiplyDoubleInt;
 double vMultiplyDoubleDouble;
-num vDivideIntInt;
-num vDivideIntDouble;
+double vDivideIntInt;
+double vDivideIntDouble;
 double vDivideDoubleInt;
 double vDivideDoubleDouble;
 int vFloorDivide;
 ''');
   }
 
   @failingTest
   test_initializer_onlyLeft() async {
     var library = await _encodeDecodeLibrary(r'''
 var a = 1;
@@ skipping 1464 matching lines @@
 
   Future<LibraryElement> _encodeDecodeLibrary(String text) async {
     String path = _p('/test.dart');
     provider.newFile(path, text);
     UnitElementResult result = await driver.getUnitElement(path);
     return result.element.library;
   }
 
   String _p(String path) => provider.convertPath(path);
 }