Merge 126839 - REGRESSION(r109480): Form state for iframe content is not restored

Merge 126839 - REGRESSION(r109480): Form state for iframe content is not restored
https://bugs.webkit.org/show_bug.cgi?id=90870

Reviewed by Jochen Eisinger.

Source/WebCore:

Since r109480, we have restored form state only for documents
loaded by FrameLoader::loadItem(). However we should restore form
state for documents in sub-frames of documents loaded by
FrameLoader::loadItem().

Test: fast/loader/form-state-restore-with-frames.html

* history/HistoryItem.cpp:
(WebCore::HistoryItem::isAncestorOf):
Added. A function to search descendants for the specified
HistoryItem. This is used by isAssociatedToRequestedHistoryItem().
* history/HistoryItem.h:
(HistoryItem): Declare isAncestorOf().
* loader/HistoryController.cpp:
(WebCore::HistoryController::saveDocumentState):
Don't save form state for detached document.
This is needed because saveDocumentState() is called twice; before
document detach and after document detach. We need to avoid the
latter call because formElementsState() for a detached document
produces an empty state.
(WebCore::isAssociatedToRequestedHistoryItem):
Added. This function checks the current HistoryItem is associated
to the HistoryItem specified to FrameLoader::loadItem().
(WebCore::HistoryController::restoreDocumentState):
Uses isAssociatedToRequestedHistoryItem().

LayoutTests:

* fast/loader/form-state-restore-with-frames.html: Added.
* fast/loader/form-state-restore-with-frames-expected.txt: Added.
* fast/loader/resources/form-state-restore-with-frames-1.html: Added.


TBR=tkent@chromium.org
Committed: https://trac.webkit.org/changeset/127221