Imported in r430168

Failing on all Debug builders (i.e. all platforms) Since

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Precise%20%28dbg%29/builds/903
https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.11%20%28dbg%29/builds/5736
https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win7%20%28dbg%29/builds/8003

Failures:
imported/wpt/html/webappapis/idle-callbacks/callback-timeout.html
imported/wpt/html/webappapis/idle-callbacks/callback-invoked.html
imported/wpt/html/browsers/the-window-object/window-open-noopener.html
imported/wpt/html/webappapis/idle-callbacks/callback-multiple-calls.html
imported/wpt/html/webappapis/idle-callbacks/callback-exception.html
imported/wpt/html/webappapis/idle-callbacks/callback-iframe.html


They appear to timeout reliably

Output like

CONSOLE ERROR: line 1: Uncaught TypeError: this.checkValues is not a function
CONSOLE ERROR: line 1: Uncaught TypeError: this.checkValues is not a function
CONSOLE ERROR: line 1: Uncaught TypeError: this.checkValues is not a function
This is a testharness.js-based test.
Harness Error. harness_status.status = 2 , harness_status.message = null
PASS window.open() with 'noopener' should not reuse existing target 
FAIL noopener needs to be present as a token on its own assert_equals: expected object "[object Window]" but got null
FAIL noopener needs to be present as a token on its own again assert_equals: expected object "[object Window]" but got null
PASS noopener needs to be present as a token on its own yet again 
TIMEOUT Trailing noopener should work Test timed out
PASS Leading noopener should work 
PASS Interior noopener should work 
NOTRUN noopener window.open targeting _self 
NOTRUN noopener window.open targeting _parent 
NOTRUN noopener window.open targeting _top 
Harness: the test ran to completion.