Check in codegen test expectations.

test/codegen/expect/language/custom_await_stack_trace_test.js

Index: test/codegen/expect/language/custom_await_stack_trace_test.js
diff --git a/test/codegen/expect/language/custom_await_stack_trace_test.js b/test/codegen/expect/language/custom_await_stack_trace_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..0f94cc5075b4b8fa948cf6b2bdbf4848b1836b05
--- /dev/null
+++ b/test/codegen/expect/language/custom_await_stack_trace_test.js
@@ -0,0 +1,52 @@
+dart_library.library('language/custom_await_stack_trace_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__custom_await_stack_trace_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const async = dart_sdk.async;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const custom_await_stack_trace_test = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  const _trace = Symbol('_trace');
+  custom_await_stack_trace_test.Blah = class Blah extends core.Object {
+    new(trace) {
+      this[_trace] = trace;
+    }
+    toString() {
+      return "Blah " + dart.notNull(dart.toString(this[_trace]));
+    }
+  };
+  custom_await_stack_trace_test.Blah[dart.implements] = () => [core.StackTrace];
+  dart.setSignature(custom_await_stack_trace_test.Blah, {
+    constructors: () => ({new: dart.definiteFunctionType(custom_await_stack_trace_test.Blah, [dart.dynamic])})
+  });
+  custom_await_stack_trace_test.foo = function() {
+    let x = "\nBloop\nBleep\n";
+    return async.Future.error(42, new custom_await_stack_trace_test.Blah(x));
+  };
+  dart.fn(custom_await_stack_trace_test.foo, VoidTodynamic());
+  custom_await_stack_trace_test.main = function() {
+    return dart.async(function*() {
+      try {
+        let x = (yield custom_await_stack_trace_test.foo());
+        expect$.Expect.fail("Should not reach here.");
+      } catch (e) {
+        if (core.int.is(e)) {
+          let s = dart.stackTrace(e);
+          expect$.Expect.equals(42, e);
+          expect$.Expect.equals("Blah \nBloop\nBleep\n", s.toString());
+          return;
+        } else
+          throw e;
+      }
+
+      expect$.Expect.fail("Unreachable.");
+    }, dart.dynamic);
+  };
+  dart.fn(custom_await_stack_trace_test.main, VoidTodynamic());
+  // Exports:
+  exports.custom_await_stack_trace_test = custom_await_stack_trace_test;
+});