Implement type inference for named function expressions.

pkg/front_end/lib/src/fasta/kernel/body_builder.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 fasta.body_builder;
 
 import 'package:kernel/ast.dart'
     hide InvalidExpression, InvalidInitializer, InvalidStatement;
 
 import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
@@ skipping 2462 matching lines @@
     pop(); // Modifiers.
     exitFunction();
 
     variable.initializer = new KernelFunctionExpression(formals.addToFunction(
         new FunctionNode(body,
             typeParameters: typeParameters, asyncMarker: asyncModifier)
           ..fileOffset = formals.charOffset
           ..fileEndOffset = endToken.charOffset))
       ..parent = variable
       ..fileOffset = formals.charOffset;
-    push(new Let(variable, new VariableGet(variable)));
+    push(
+        new KernelNamedFunctionExpression(variable, new VariableGet(variable)));
   }
 
   @override
   void endLocalFunctionDeclaration(Token token) {
     debugEvent("LocalFunctionDeclaration");
     Statement body = popStatement();
     AsyncMarker asyncModifier = pop();
     if (functionNestingLevel != 0) {
       exitLocalScope();
     }
@@ skipping 1307 matching lines @@
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return unhandled(asyncToken.lexeme, "asyncMarkerFromTokens",
         asyncToken.charOffset, null);
   }
 }