Revert of IDL: Treat undefined as missing for optional arguments with defaults (https://codereview.chromium.org/373043004/)

Reason for revert:
The following layout tests fail on Mac:
fast/css/shorthand-setProperty-important.html
fast/dom/Comment/comment-constructor.html
fast/dom/DOMImplementation/createHTMLDocument-optional-title.html
fast/dom/HTMLDialogElement/dialog-return-value.html
fast/dom/NodeIterator/NodeIterator-basic.html
fast/dom/Text/text-constructor.html
fast/dom/TreeWalker/TreeWalker-basic.html
fast/dom/Window/custom-constructors.html
fast/dom/Window/alert-undefined.html
fast/encoding/api/basics.html
fast/js/custom-constructors.html
fast/workers/shared-worker-name.html
media/encrypted-media/encrypted-media-istypesupported.html

Original issue's description:
> IDL: Treat undefined as missing for optional arguments with defaults
> 
> For optional arguments with defaults, treat undefined as missing simply
> by checking 'info[N].IsUndefined()' instead of 'N <= info.Length()'.
> 
> This works since V8's indexing operator returns an undefined value for
> all out-of-range indexes.
> 
> Changes in behavior that had (or now has) testing coverade matches
> Firefox (Nightly), except in the case of WebKitCSSMatrix's constructor,
> which Firefox naturally doesn't have.
> 
> BUG=335871
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177857

TBR=haraken@chromium.org,arv@chromium.org,jl@opera.com
NOTREECHECKS=true
NOTRY=true
BUG=335871

Review URL: https://codereview.chromium.org/382833003

git-svn-id: svn://svn.chromium.org/blink/trunk@177866 bbb929c8-8fbe-4397-9dbb-9b2b20218538