[gin] Use variadic templates in gin/function_template.h

[gin] Use variadic templates in gin/function_template.h

Replace pump.py generated gin/function_template.h with variadic template version.

This results in a concise code which does not require the use
of pump preprocessor.
Similar effort for base/callback.h is happening in https://codereview.chromium.org/610423003/

BUG=

Committed: https://crrev.com/735c49b6ad67166ccbcc8e3717681bb560fbf1cf
Cr-Commit-Position: refs/heads/master@{#301089}

[Krzysztof Olczyk, 2014-10-23 11:51:04]

kolczyk@opera.com changed reviewers:
+ abarth@chromium.org, jochen@chromium.org

[Krzysztof Olczyk, 2014-10-23 11:51:05]

Hi abarth & jochen,

could you please take a look at this CL
which intends to modernize function_template.h in gin
thanks to the variadic templates having been allowed
in Chromium code?

[jochen (gone - plz use gerrit), 2014-10-24 11:34:15]

lgtm

[Krzysztof Olczyk, 2014-10-24 11:41:47]

The CQ bit was checked by kolczyk@opera.com

[commit-bot: I haz the power, 2014-10-24 11:42:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/671433004/20001

[commit-bot: I haz the power, 2014-10-24 13:06:16]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-10-24 13:07:00]

Patchset 2 (id:??) landed as
https://crrev.com/735c49b6ad67166ccbcc8e3717681bb560fbf1cf
Cr-Commit-Position: refs/heads/master@{#301089}

[Aaron Boodman, 2014-10-31 22:26:39]

aa@chromium.org changed reviewers:
+ aa@chromium.org

[Aaron Boodman, 2014-10-31 22:26:40]

Cool, this was on my list of things to do. Thanks!

https://codereview.chromium.org/671433004/diff/20001/gin/function_template.h
File gin/function_template.h (right):

https://codereview.chromium.org/671433004/diff/20001/gin/function_template.h#...
gin/function_template.h:1: // Copyright 2014 The Chromium Authors. All rights
reserved.
I thought we weren't supposed to change the year.

https://codereview.chromium.org/671433004/diff/20001/gin/function_template.h#...
gin/function_template.h:133: : ok(GetNextArgument(args, create_flags, index ==
0, &value)) {
Out of curiosity, since you have |index| already, if we changed gin::Arguments
to have a getter by index, could we use that and avoid the slighty scary comment
about below initialization order?

[Krzysztof Olczyk, 2014-11-05 07:50:40]

https://codereview.chromium.org/671433004/diff/20001/gin/function_template.h
File gin/function_template.h (right):

https://codereview.chromium.org/671433004/diff/20001/gin/function_template.h#...
gin/function_template.h:133: : ok(GetNextArgument(args, create_flags, index ==
0, &value)) {
On 2014/10/31 22:26:40, Aaron Boodman wrote:
> Out of curiosity, since you have |index| already, if we changed gin::Arguments
> to have a getter by index, could we use that and avoid the slighty scary
comment
> about below initialization order?

Yes, we could have probably used the index directly if gin::Arguments supported
it, but it might have complicated the code - taking into account the fact that
we do not directly iterate over gin::Arguments, as some of the arguments can be
gin::Arguments* or v8::Isolate*. 
So, we would have needed to know at which position they were and add adequate
offsets.