[turbofan] Remove kInterpreterDispatch CallDescriptor kind in favor of flag.

[turbofan] Remove kInterpreterDispatch CallDescriptor kind in favor of flag.

Rationale: The {kind} of a call descriptor describes what the {target} being
called is--i.e. a JSFunction, code object, or address. That kind materially
dictates the instruction(s) generated for an outgoing call.

The other flags on a call descriptor should describe specific properties
(like whether a roots register is valid or not) so that backend logic doesn't
have to switch over the kind, but is informed directly of what it wants to
know.

R=mstarzinger@chromium.org
BUG=

Committed: https://crrev.com/8b56ec9ccc66496d631ca32d372480f0964cbb7d
Cr-Commit-Position: refs/heads/master@{#30065}

[Michael Starzinger, 2015-08-07 11:26:13]

LGTM. I like it.

[titzer, 2015-08-07 11:29:42]

The CQ bit was checked by titzer@chromium.org

[commit-bot: I haz the power, 2015-08-07 11:29:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1268273003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1268273003/1

[commit-bot: I haz the power, 2015-08-07 11:46:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-07 11:46:26]

Patchset 1 (id:??) landed as
https://crrev.com/8b56ec9ccc66496d631ca32d372480f0964cbb7d
Cr-Commit-Position: refs/heads/master@{#30065}