<http://webkit.org/b/74768>

Reviewed by Antti Koivisto.

Source/WebCore: 

Let Document cache the document.all collection, just like we do for
the other collections (.links, .images, etc.)
This is primarily a memory optimization, as repeated calls to
document.all will no longer cause collection objects to stack up.

Tests: fast/dom/document-collection-idempotence.html
       fast/dom/gc-9.html

* dom/Document.h:
* dom/Document.cpp:
(WebCore::Document::all):

    Cache the HTMLAllCollection and reuse it across calls instead of
    creating a new one each time.

* html/HTMLAllCollection.h:
* html/HTMLAllCollection.cpp:
(WebCore::HTMLAllCollection::create):
(WebCore::HTMLAllCollection::HTMLAllCollection):

    Make the HTMLAllCollection constructor take a Document* to enforce
    the fact that it's the only way it should ever be created.

* html/HTMLAllCollection.idl:
* bindings/scripts/CodeGeneratorJS.pm:
(GenerateImplementation):

    Custom reachability code for JSC, same as HTMLCollection.

LayoutTests: 

Update tests to document the new behavior of document.all.

* fast/dom/document-collection-idempotence-expected.txt:
* fast/dom/document-collection-idempotence.html:
* fast/dom/gc-9-expected.txt:
* fast/dom/gc-9.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@103166 268f45cc-cd09-0410-ab3c-d52691b4dbfc