Revert of Traverse PDF page tree only once in CPDF_Document Try 2 (patchset #3 id:40001 of https://codereview.chromium.org/2442403002/ )

Reason for revert:
Not quite right yet.

Original issue's description:
> Traverse PDF page tree only once in CPDF_Document
>
> Try 2: main fix was recursively popping elements from the stack. Since
> the Traverse method can be called on non-root nodes from GetPage(), we
> have to make sure to properly update the parents.
>
> Try 1 at https://codereview.chromium.org/2414423002/
>
> In our current implementation of CPDF_Document::GetPage, we traverse
> the PDF page tree until we find the index we are looking for. This is
> slow when we do calls GetPage(0), GetPage(1), ... since in this case
> the page tree will be traversed n times if there are n pages. This CL
> makes sure the page tree is only traversed once.
>
> Time to load the PDF from the bug below in chrome official build:
> Before this CL: around 1 minute 25 seconds
> After this CL: around 4 seconds
>
> BUG=chromium:638513
>
> Committed: https://pdfium.googlesource.com/pdfium/+/d3a2009d75eac3cda442f545ef0865afae7b35cf

TBR=tsepez@chromium.org,weili@chromium.org,thestig@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=chromium:638513

Review-Url: https://codereview.chromium.org/2461063003

0 files changed, 0 insertions, 0 deletions