diff --git a/implementation-contributed/v8/mjsunit/regress/regress-748069.js b/implementation-contributed/v8/mjsunit/regress/regress-748069.js
index e652cca67232541f9d046150cbe733be63e3f704..86c2f8f5ec334c25e0404f92b3f70b93d79a7208 100644
--- a/implementation-contributed/v8/mjsunit/regress/regress-748069.js
+++ b/implementation-contributed/v8/mjsunit/regress/regress-748069.js
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// This test gets very slow with slow asserts.
+// Flags: --noenable-slow-asserts
+
 try {
   var a = 'a'.repeat(1 << 28);
 } catch (e) {
diff --git a/implementation-contributed/v8/mjsunit/regress/regress-908975.js b/implementation-contributed/v8/mjsunit/regress/regress-908975.js
new file mode 100644
index 0000000000000000000000000000000000000000..b80f4ce9c4b3576c2d8ba702450b8e8309cf4a20
--- /dev/null
+++ b/implementation-contributed/v8/mjsunit/regress/regress-908975.js
@@ -0,0 +1,6 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[] = [];
+a => 0
diff --git a/implementation-contributed/v8/wasm-js/testharness.js b/implementation-contributed/v8/wasm-js/testharness.js
index ecaf0b82d9bc83ffec9d89aa3fbd95a867e23c41..904a973519e5c1cf22073a9179ef82ece05dbd06 100644
--- a/implementation-contributed/v8/wasm-js/testharness.js
+++ b/implementation-contributed/v8/wasm-js/testharness.js
@@ -19,7 +19,7 @@ let lastPromise = Promise.resolve();
 
 function test(func, description) {
   let maybeErr;
-  try { func({unreached_func: assert_unreached}); }
+  try { func({unreached_func: unreached_func}); }
   catch(e) { maybeErr = e; }
   if (typeof maybeErr !== 'undefined') {
     console.log(`${description}: FAIL. ${maybeErr}`);
@@ -98,6 +98,12 @@ function assert_array_equals(actual, expected, description) {
   }
 }
 
+function unreached_func(msg) {
+  return function trap() {
+    assert_unreached(msg);
+  };
+}
+
 function assert_unreached(description) {
   throw new Error(`unreachable:\n${description}`);
 }