Check in codegen test expectations.

test/codegen/expect/language/propagate_past_constant_test.js

+dart_library.library('language/propagate_past_constant_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__propagate_past_constant_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 propagate_past_constant_test = Object.create(null);
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  propagate_past_constant_test.foo = function(x) {
+    return x;
+  };
+  dart.fn(propagate_past_constant_test.foo, dynamicTodynamic());
+  propagate_past_constant_test.check = function(y) {
+    expect$.Expect.equals('foo', y);
+  };
+  dart.fn(propagate_past_constant_test.check, dynamicTodynamic());
+  propagate_past_constant_test.main = function() {
+    let x = propagate_past_constant_test.foo('foo');
+    let y = propagate_past_constant_test.foo(x);
+    x = 'constant';
+    propagate_past_constant_test.check(y);
+    propagate_past_constant_test.foo(x);
+    propagate_past_constant_test.foo(x);
+  };
+  dart.fn(propagate_past_constant_test.main, VoidTodynamic());
+  // Exports:
+  exports.propagate_past_constant_test = propagate_past_constant_test;
+});