Check in codegen test expectations.

test/codegen/expect/language/null2_test.js

+dart_library.library('language/null2_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__null2_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 null2_test = Object.create(null);
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  null2_test.confuse = function(x) {
+    try {
+      if (new core.DateTime.now().millisecondsSinceEpoch == 42) x = 42;
+      dart.throw([x]);
+    } catch (e) {
+      if (dart.dynamic.is(e)) {
+        return dart.dindex(e, 0);
+      } else
+        throw e;
+    }
+
+    return 42;
+  };
+  dart.fn(null2_test.confuse, dynamicTodynamic());
+  null2_test.main = function() {
+    expect$.Expect.equals("Null", dart.toString(dart.runtimeType(null)));
+    expect$.Expect.equals("Null", dart.toString(dart.runtimeType(null2_test.confuse(null))));
+  };
+  dart.fn(null2_test.main, VoidTodynamic());
+  // Exports:
+  exports.null2_test = null2_test;
+});