Reapply "Add support for generic function type syntax, part 1"

pkg/analyzer/tool/summary/generate.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.
 
 /**
  * This file contains code to generate serialization/deserialization logic for
  * summaries based on an "IDL" description of the summary format (written in
  * stylized Dart).
  *
  * For each class in the "IDL" input, two corresponding classes are generated:
@@ skipping 250 matching lines @@
         _idl.classes[clsName] = cls;
         String expectedBase = 'base.SummaryClass';
         if (decl.extendsClause == null ||
             decl.extendsClause.superclass.name.name != expectedBase) {
           throw new Exception(
               'Class `$clsName` needs to extend `$expectedBase`');
         }
         for (ClassMember classMember in decl.members) {
           if (classMember is MethodDeclaration && classMember.isGetter) {
             String desc = '$clsName.${classMember.name.name}';
+            if (classMember.returnType is! TypeName) {
+              if (classMember.returnType == null) {
+                throw new Exception('Class member needs a type: $desc');
+              }
+              throw new Exception('Class member needs a class type: $desc');
+            }
             TypeName type = classMember.returnType;
-            if (type == null) {
-              throw new Exception('Class member needs a type: $desc');
-            }
             bool isList = false;
             if (type.name.name == 'List' &&
                 type.typeArguments != null &&
                 type.typeArguments.arguments.length == 1) {
               isList = true;
               type = type.typeArguments.arguments[0];
             }
             if (type.typeArguments != null) {
               throw new Exception('Cannot handle type arguments in `$type`');
             }
@@ skipping 739 matching lines @@
       return token.lexeme.split('\n').map((String line) {
         if (line.startsWith(indent)) {
           line = line.substring(indent.length);
         }
         return line;
       }).join('\n');
     }
     return null;
   }
 }