fix #27408, reverts "ignore dynamic in inference"

pkg/dev_compiler/test/codegen_expected/varargs.js

Index: pkg/dev_compiler/test/codegen_expected/varargs.js
diff --git a/pkg/dev_compiler/test/codegen_expected/varargs.js b/pkg/dev_compiler/test/codegen_expected/varargs.js
index 326b1d237f3b83863b0bef3b1279bed878f0d8f9..295c642b559d9e25a927f0307f174547b2546e47 100644
--- a/pkg/dev_compiler/test/codegen_expected/varargs.js
+++ b/pkg/dev_compiler/test/codegen_expected/varargs.js
@@ -1,21 +1,19 @@
 define(['dart_sdk'], function(dart_sdk) {
   'use strict';
   const core = dart_sdk.core;
-  const _interceptors = dart_sdk._interceptors;
   const dart = dart_sdk.dart;
   const dartx = dart_sdk.dartx;
   const varargs = Object.create(null);
   const src__varargs = Object.create(null);
-  let JSArrayOfint = () => (JSArrayOfint = dart.constFn(_interceptors.JSArray$(core.int)))();
   let dynamicAnddynamicTodynamic = () => (dynamicAnddynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic, dart.dynamic])))();
   let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
   varargs.varargsTest = function(x, ...others) {
-    let args = JSArrayOfint().of([1, core.int._check(others)]);
+    let args = [1, others];
     dart.dcall(x, ...args);
   };
   dart.fn(varargs.varargsTest, dynamicAnddynamicTodynamic());
   varargs.varargsTest2 = function(x, ...others) {
-    let args = JSArrayOfint().of([1, core.int._check(others)]);
+    let args = [1, others];
     dart.dcall(x, ...args);
   };
   dart.fn(varargs.varargsTest2, dynamicAnddynamicTodynamic());