[runtime] Remove obsolete Object::IsSpecFunction.

[runtime] Remove obsolete Object::IsSpecFunction.

We don't need Object::IsSpecFunction anymore, since it only checks for
JSFunction and JSFunctionProxy, but what you actually want to check for
(in case of accessors) is whether the target has a [[Call]] internal
method, which is exactly what Object::IsCallable does.

CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_linux_layout_dbg,v8_linux_nosnap_dbg
R=rossberg@chromium.org
BUG=v8:4413
LOG=n

Committed: https://crrev.com/91c495ff446363b480aee3a980dcb5006dca5692
Cr-Commit-Position: refs/heads/master@{#30875}

[Benedikt Meurer, 2015-09-23 04:37:44]

The CQ bit was checked by bmeurer@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-23 04:38:02]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1358403002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1358403002/1

[Benedikt Meurer, 2015-09-23 04:38:02]

Hey Andreas,

This is trivial cleanup.
Please take a look.

Thanks,
Benedikt

[rossberg, 2015-09-23 05:37:26]

lgtm

[Benedikt Meurer, 2015-09-23 05:42:32]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2015-09-23 05:42:37]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-09-23 05:42:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1358403002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1358403002/1

[commit-bot: I haz the power, 2015-09-23 05:53:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-23 05:53:49]

Patchset 1 (id:??) landed as
https://crrev.com/91c495ff446363b480aee3a980dcb5006dca5692
Cr-Commit-Position: refs/heads/master@{#30875}