Remove testRunner.displayAsync() and displayAsyncThen()

Remove testRunner.displayAsync() and displayAsyncThen()

Blink tests have been modified to use the new layoutAndPaintAsync()
and layoutAndPaintAsyncThen().

BUG=484706
Committed: https://crrev.com/bde8d4b699117944cd8a7734aaf7ad6c96cb56d2
Cr-Commit-Position: refs/heads/master@{#329278}

[Xianzhu, 2015-05-08 16:28:11]

wangxianzhu@chromium.org changed reviewers:
+ dpranke@chromium.org

[Xianzhu, 2015-05-11 17:52:11]

wangxianzhu@chromium.org changed reviewers:
+ mkwst@chromium.org, tkent@chromium.org

[tkent, 2015-05-11 22:44:39]

The CQ bit was checked by tkent@chromium.org

[tkent, 2015-05-11 22:44:40]

lgtm

[commit-bot: I haz the power, 2015-05-11 22:46:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1131803003/1

[Dirk Pranke, 2015-05-11 23:40:31]

lgtm

[commit-bot: I haz the power, 2015-05-11 23:47:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-11 23:49:54]

Patchset 1 (id:??) landed as
https://crrev.com/bde8d4b699117944cd8a7734aaf7ad6c96cb56d2
Cr-Commit-Position: refs/heads/master@{#329278}