[turbofan] Support unboxed float and double stack parameters and add tests.

[turbofan] Support unboxed float and double stack parameters and add tests.

R=jarin@chromium.org
BUG=

Committed: https://crrev.com/0492bb3291c838d7e11261abc32af58bed58bcf0
Cr-Commit-Position: refs/heads/master@{#30203}

[titzer, 2015-08-17 13:24:47]

PTAL: small tweaks to code generators and instruction selectors to handle
float32/float64 passed on the stack.

I plan to clean this up in the near future by refactoring CallDescriptor to
contain an array of pushed arguments.

[Jarin, 2015-08-17 14:01:56]

lgtm.

However, I am not a big fan of the 'if (Node* node = ...)' pattern, especially
when there is a 'node' variable in the outer scope, so it can be easily misread
as if (node == ...)'.

[titzer, 2015-08-17 17:33:43]

The CQ bit was checked by titzer@chromium.org

[titzer, 2015-08-17 17:33:43]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/1291113003/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-08-17 17:33:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1291113003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1291113003/20001

[commit-bot: I haz the power, 2015-08-17 17:35:44]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-17 17:36:02]

Patchset 2 (id:??) landed as
https://crrev.com/0492bb3291c838d7e11261abc32af58bed58bcf0
Cr-Commit-Position: refs/heads/master@{#30203}

[titzer, 2015-08-17 17:58:44]

On 2015/08/17 14:01:56, Jarin wrote:
> lgtm.
> 
> However, I am not a big fan of the 'if (Node* node = ...)' pattern, especially
> when there is a 'node' variable in the outer scope, so it can be easily
misread
> as if (node == ...)'.

I fixed the shadowing of the variable in the outer scope.