Pull in the latest upstream testharness.js changes.

Pull in the latest upstream testharness.js changes.

This pull in the latest changes from the testharness.js repository:
  https://github.com/w3c/testharness.js

Bug fixes, new idlharness functionality, and so on. This is required
for importing new/updated tests from web-platform-tests.

Mainly just a copy/paste of testharness.js and idlharness.js.
A few failing expectations needed updating due to output changes,
and one test that now spews a stack is tweaked to use
testharnessreport.js to ensure consistent output across our bots.

R=dpranke@chromium.org
BUG=433962
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=194416

[jsbell, 2015-04-23 23:47:56]

dpranke@ - please take a look?

Just copy/paste from tip-of-tree to all findable copies of testharness.js and
idlharness.js

[Dirk Pranke, 2015-04-24 00:38:10]

rubber-stamp lgtm. Should we be importing the docs/ directory that these files
all reference, now?

[jsbell, 2015-04-24 18:15:17]

On 2015/04/24 00:38:10, Dirk Pranke wrote:
> Should we be importing the docs/ directory that these files
> all reference, now?

Good point. I filed crbug.com/481113 to add a README next to the testharness.js
copies, rather than importing the docs too, but we can iterate.

[jsbell, 2015-04-24 18:17:46]

The CQ bit was checked by jsbell@chromium.org

[jsbell, 2015-04-24 18:17:47]

The patchset sent to the CQ was uploaded after l-g-t-m from dpranke@chromium.org
Link to the patchset: https://codereview.chromium.org/1061543006/#ps20001
(title: "Rebase/tweaks for affected tests")

[commit-bot: I haz the power, 2015-04-24 18:18:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1061543006/20001

[commit-bot: I haz the power, 2015-04-24 18:24:03]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-24 18:24:03]

Try jobs failed on following builders:
  android_blink_compile_dbg on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/android_blink_compile_db...)

[jsbell, 2015-04-24 18:52:09]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2015-04-24 18:52:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1061543006/20001

[commit-bot: I haz the power, 2015-04-24 20:03:24]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=194416