Fix assert triggered by constant folding.

Fix assert triggered by constant folding.

Add<> asserts the return type, which might not be an HAdd in this case
because of constant folding.

BUG=
R=jkummerow@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=16414

[Jakob Kummerow, 2013-08-29 09:52:11]

LGTM with comment.

https://codereview.chromium.org/23754002/diff/1/src/hydrogen.cc
File src/hydrogen.cc (right):

https://codereview.chromium.org/23754002/diff/1/src/hydrogen.cc#newcode1546
src/hydrogen.cc:1546: HValue* min_growth = AddUncasted<HConstant>(16);
You can keep the plain "Add" here.

[Benedikt Meurer, 2013-08-29 09:54:09]

IMHO we need some way for the compiler to detect this. I.e. Add<XZY>(...) should
fail to compile if XZY::New() does not necessarily return an XYZ.

[oliv, 2013-08-29 09:54:59]

Committed patchset #2 manually as r16414 (presubmit successful).

[oliv, 2013-08-29 09:56:17]

On 2013/08/29 09:54:09, Benedikt Meurer wrote:
> IMHO we need some way for the compiler to detect this. I.e. Add<XZY>(...)
should
> fail to compile if XZY::New() does not necessarily return an XYZ.

oh i agree, but i just wanted to fix this since it broke on octane....