Reify type params on map literals

test/codegen_expected/language/const_map_test.js

 dart_library.library('language/const_map_test', null, /* Imports */[
   'dart_sdk',
   'expect'
 ], function load__const_map_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 const_map_test = Object.create(null);
   let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
   let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
   const_map_test.confuse = function(x) {
     if (dart.equals(new core.DateTime.now(), 42)) return const_map_test.confuse(2);
     return x;
   };
   dart.fn(const_map_test.confuse, dynamicTodynamic());
   let const$;
   const_map_test.main = function() {
-    let m = const$ || (const$ = dart.const(dart.map([1, 42, "foo", 499])));
+    let m = const$ || (const$ = dart.const(dart.map([1, 42, "foo", 499], core.Object, core.int)));
     expect$.Expect.equals(42, m[dartx.get](const_map_test.confuse(1.0)));
     expect$.Expect.equals(499, m[dartx.get](const_map_test.confuse(core.String.fromCharCodes("foo"[dartx.runes]))));
   };
   dart.fn(const_map_test.main, VoidTodynamic());
   // Exports:
   exports.const_map_test = const_map_test;
 });