Check in codegen test expectations.

test/codegen/expect/lib/math/low_test.js

Index: test/codegen/expect/lib/math/low_test.js
diff --git a/test/codegen/expect/lib/math/low_test.js b/test/codegen/expect/lib/math/low_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..da86b55d7cd4e73ad6f2dc1e35388d23e6efc90d
--- /dev/null
+++ b/test/codegen/expect/lib/math/low_test.js
@@ -0,0 +1,33 @@
+dart_library.library('lib/math/low_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__low_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const math = dart_sdk.math;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const low_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  low_test.main = function() {
+    let n = (2 * (1)[dartx['<<']](32) / 3)[dartx.truncate]();
+    let n2 = (n / 2)[dartx.truncate]();
+    let iterations = 200000;
+    let seed = math.Random.new().nextInt(1 << 16);
+    core.print(dart.str`low_test seed: ${seed}`);
+    let prng = math.Random.new(seed);
+    let low = 0;
+    for (let i = 0; i < iterations; i++) {
+      if (dart.notNull(prng.nextInt(n)) < n2) {
+        low++;
+      }
+    }
+    let diff = (low - (iterations / 2)[dartx.truncate]())[dartx.abs]();
+    core.print(dart.str`${low}, ${diff}`);
+    expect$.Expect.isTrue(dart.notNull(diff) < (iterations / 20)[dartx.truncate]());
+  };
+  dart.fn(low_test.main, VoidTovoid());
+  // Exports:
+  exports.low_test = low_test;
+});