Add primitive to create closures and use it for closure conversion

pkg/kernel/lib/type_checker.dart

 // Copyright (c) 2016, 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 kernel.type_checker;
 
 import 'ast.dart';
 import 'class_hierarchy.dart';
 import 'core_types.dart';
 import 'type_algebra.dart';
 import 'type_environment.dart';
@@ skipping 672 matching lines @@
   DartType visitLoadLibrary(LoadLibrary node) {
     return environment.futureType(const DynamicType());
   }
 
   @override
   DartType visitCheckLibraryIsLoaded(CheckLibraryIsLoaded node) {
     return environment.objectType;
   }
 
   @override
+  DartType visitVectorCreation(VectorCreation node) {
+    return const VectorType();
+  }
+
+  @override
   DartType visitVectorGet(VectorGet node) {
     var type = visitExpression(node.vectorExpression);
     if (type is! VectorType) {
       fail(
           node.vectorExpression,
           'The type of vector-expression in vector-get node is expected to be '
           'VectorType, but $type found');
     }
     return const DynamicType();
   }
@@ skipping 16 matching lines @@
     if (type is! VectorType) {
       fail(
           node.vectorExpression,
           'The type of vector-expression in vector-copy node is exected to be '
           'VectorType, but $type found');
     }
     return const VectorType();
   }
 
   @override
-  DartType visitVectorCreation(VectorCreation node) {
-    return const VectorType();
+  visitClosureCreation(ClosureCreation node) {
+    var contextType = visitExpression(node.contextVector);
+    if (contextType is! VectorType) {
+      fail(
+          node.contextVector,
+          "The second child of 'ClosureConversion' node is supposed to be a "
+          "Vector, but $contextType found.");
+    }
+    return node.functionType;
   }
 
   @override
   visitAssertStatement(AssertStatement node) {
     visitExpression(node.condition);
     if (node.message != null) {
       visitExpression(node.message);
     }
   }
 
@@ skipping 202 matching lines @@
   }
 
   @override
   visitLocalInitializer(LocalInitializer node) {
     visitVariableDeclaration(node.variable);
   }
 
   @override
   visitInvalidInitializer(InvalidInitializer node) {}
 }