IDL: Avoid double type-check for variadic interface type arguments

IDL: Avoid double type-check for variadic interface type arguments

With [TypeChecking=Interface], two type-checks would be emitted for
variadic arguments; one as if the argument wasn't variadic, checking only
the first actual argument, and then another one checking each actual
argument.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177094

[Jens Widell, 2014-06-27 10:47:27]

PTAL

Another unexpected CG change noticed when adding [TypeChecking=Interface] on the
Document interface, affecting the method

  [RuntimeEnabled=Touch] TouchList createTouchList(Touch... touches);

Fixing this isn't strictly required; we just generate code for checking the
first argument twice.

[haraken, 2014-06-27 11:00:11]

LGTM

[Jens Widell, 2014-06-27 11:02:03]

The CQ bit was checked by jl@opera.com

[commit-bot: I haz the power, 2014-06-27 11:02:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jl@opera.com/359763002/20001

[commit-bot: I haz the power, 2014-06-27 12:03:27]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_gn_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_chromium_gn_rel/bu...)

[commit-bot: I haz the power, 2014-06-27 12:12:38]

Change committed as 177094