Fix HType handling for HConstant with external references.

Fix HType handling for HConstant with external references.

We cannot use set_type() with HType::None() in the HConstant
constructor, since set_type() asserts that the new type is a
subtype of the previous one, but HType::None() is not a subtype
of HType::Tagged() which is the initial type set by the HValue
constructor.

This patch adds an optional type parameter to the HValue,
HInstruction and HTemplateInstruction constructors.

R=titzer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=15980

[Benedikt Meurer, 2013-07-31 09:22:30]

Hey Ben,
This is the HConstant with HType::None() change we discussed a few minutes ago.
-- Benedikt

[titzer, 2013-07-31 09:32:36]

LGTM

Note that I just added some more set_type() calls in constructors. We can use
the constructor that you've added now, but I'll leave it up to you if you want
to do that in this CL as well.

[Benedikt Meurer, 2013-07-31 09:37:59]

On 2013/07/31 09:32:36, titzer wrote:
> LGTM
> 
> Note that I just added some more set_type() calls in constructors. We can use
> the constructor that you've added now, but I'll leave it up to you if you want
> to do that in this CL as well.

I'll just land this one because it's required for the HLinkObjectInList removal
CL. Will prepare a follow-up CL with cleanups.

[Benedikt Meurer, 2013-07-31 09:38:44]

Committed patchset #1 manually as r15980 (presubmit successful).