Check in codegen test expectations.

test/codegen/expect/language/unicode_bom_middle_test.js

+dart_library.library('language/unicode_bom_middle_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__unicode_bom_middle_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 unicode_bom_middle_test = Object.create(null);
+  let intToint = () => (intToint = dart.constFn(dart.definiteFunctionType(core.int, [core.int])))();
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  unicode_bom_middle_test.inscrutable = function(x) {
+    return x == 0 ? 0 : (dart.notNull(x) | dart.notNull(unicode_bom_middle_test.inscrutable((dart.notNull(x) & dart.notNull(x) - 1) >>> 0))) >>> 0;
+  };
+  dart.fn(unicode_bom_middle_test.inscrutable, intToint());
+  unicode_bom_middle_test.foo = function(x) {
+    if (unicode_bom_middle_test.inscrutable(1999) == 1999) return x;
+    return 499;
+  };
+  dart.fn(unicode_bom_middle_test.foo, dynamicTodynamic());
+  unicode_bom_middle_test.main = function() {
+    expect$.Expect.equals(3, "xx"[dartx.length]);
+    expect$.Expect.equals(3, dart.dload(unicode_bom_middle_test.foo("xx"), 'length'));
+  };
+  dart.fn(unicode_bom_middle_test.main, VoidTodynamic());
+  // Exports:
+  exports.unicode_bom_middle_test = unicode_bom_middle_test;
+});