Add d8 API for spawning function on a new thread (Second try)

Add d8 API for spawning function on a new thread (Second try)

This API closely matches the Worker API. The differences:

1) The argument to the Worker constructor is a function to run, not a script.
2) Receiving a message from a worker is a synchronous API (as there is no event
loop).

The serialization done here is not robust as the real DOM implementation. For
example, recursive data structures or otherwise duplicated objects are not
allowed.

BUG=chromium:497295
R=jochen@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1185643004

Cr-Commit-Position: refs/heads/master@{#29126}

Committed: https://crrev.com/ec2eaf712ecee6b4891c0458f2397e04a1f9b339
Cr-Commit-Position: refs/heads/master@{#29158}

[binji, 2015-06-18 21:57:57]

Reverted last change because it broke the shared builders + Arm builder.

Patch #1 is previous, patch #2 has fixes.

[binji, 2015-06-19 06:00:24]

Patchset #3 (id:40001) has been deleted

[jochen (gone - plz use gerrit), 2015-06-19 06:36:40]

lgtm

[binji, 2015-06-19 16:10:52]

The CQ bit was checked by binji@chromium.org

[commit-bot: I haz the power, 2015-06-19 16:11:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1195613003/60001

[commit-bot: I haz the power, 2015-06-19 16:13:02]

Committed patchset #3 (id:60001)

[commit-bot: I haz the power, 2015-06-19 16:13:18]

Patchset 3 (id:??) landed as
https://crrev.com/ec2eaf712ecee6b4891c0458f2397e04a1f9b339
Cr-Commit-Position: refs/heads/master@{#29158}

[binji, 2015-06-19 18:31:44]

A revert of this CL (patchset #3 id:60001) has been created in
https://codereview.chromium.org/1191373005/ by binji@chromium.org.

The reason for reverting is: Fails on V8 Linux - isolates
(http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20isolates/buil...).