Reify type params on map literals

test/codegen_expected/language/regress_23046_test.js

 dart_library.library('language/regress_23046_test', null, /* Imports */[
   'dart_sdk',
   'expect'
 ], function load__regress_23046_test(exports, dart_sdk, expect) {
   'use strict';
   const core = dart_sdk.core;
   const dart = dart_sdk.dart;
   const dartx = dart_sdk.dartx;
   const expect$ = expect.expect;
   const regress_23046_test = Object.create(null);
   let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
   regress_23046_test.y = 'foo';
   regress_23046_test.x = dart.str`${regress_23046_test.y}"`;
-  regress_23046_test.m = dart.const(dart.map([regress_23046_test.x, 0, regress_23046_test.y, 1]));
+  regress_23046_test.m = dart.const(dart.map([regress_23046_test.x, 0, regress_23046_test.y, 1], core.String, core.int));
   regress_23046_test.main = function() {
     expect$.Expect.equals(regress_23046_test.x, 'foo"');
     expect$.Expect.equals(regress_23046_test.m[dartx.length], 2);
   };
   dart.fn(regress_23046_test.main, VoidTodynamic());
   // Exports:
   exports.regress_23046_test = regress_23046_test;
 });