Revert of Traverse PDF page tree only once in CPDF_Document

Revert of Traverse PDF page tree only once in CPDF_Document (patchset #4 id:60001 of https://codereview.chromium.org/2414423002/ )

Reason for revert:
Possible cause of crbug.com/657897 reverting to find out.

BUG=657897
Original issue's description:
> Traverse PDF page tree only once in CPDF_Document
> 
> 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: 1 minute 40 seconds
> After this CL: 5 seconds
> 
> BUG=chromium:638513
> 
> Committed: https://pdfium.googlesource.com/pdfium/+/7c29e27dae139a205755c1a29b7f3ac8b36ec0da

TBR=thestig@chromium.org,tsepez@chromium.org,npm@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=chromium:638513
Committed: https://pdfium.googlesource.com/pdfium/+/7403f8a2a0d87179a1ccd57ceccd2d84fa59c319

[dsinclair, 2016-10-20 17:23:33]

The CQ bit was checked by dsinclair@chromium.org

[dsinclair, 2016-10-20 17:23:33]

Created Revert of Traverse PDF page tree only once in CPDF_Document

[commit-bot: I haz the power, 2016-10-20 17:23:37]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Tom Sepez, 2016-10-20 17:41:22]

stampy stamp LGTM

[commit-bot: I haz the power, 2016-10-20 17:50:26]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-20 17:50:27]

Try jobs failed on following builders:
  android on master.tryserver.client.pdfium (JOB_FAILED,
https://build.chromium.org/p/tryserver.client.pdfium/builders/android/builds/...)

[dsinclair, 2016-10-20 17:50:54]

The CQ bit was checked by dsinclair@chromium.org

[commit-bot: I haz the power, 2016-10-20 17:50:57]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-20 17:58:54]

Description was changed from

==========
Revert of Traverse PDF page tree only once in CPDF_Document (patchset #4
id:60001 of https://codereview.chromium.org/2414423002/ )

Reason for revert:
Possible cause of crbug.com/657897 reverting to find out.

BUG=657897

Original issue's description:
> Traverse PDF page tree only once in CPDF_Document
> 
> 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: 1 minute 40 seconds
> After this CL: 5 seconds
> 
> BUG=chromium:638513
> 
> Committed:
https://pdfium.googlesource.com/pdfium/+/7c29e27dae139a205755c1a29b7f3ac8b36e...

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

to

==========
Revert of Traverse PDF page tree only once in CPDF_Document (patchset #4
id:60001 of https://codereview.chromium.org/2414423002/ )

Reason for revert:
Possible cause of crbug.com/657897 reverting to find out.

BUG=657897

Original issue's description:
> Traverse PDF page tree only once in CPDF_Document
> 
> 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: 1 minute 40 seconds
> After this CL: 5 seconds
> 
> BUG=chromium:638513
> 
> Committed:
https://pdfium.googlesource.com/pdfium/+/7c29e27dae139a205755c1a29b7f3ac8b36e...

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

Committed:
https://pdfium.googlesource.com/pdfium/+/7403f8a2a0d87179a1ccd57ceccd2d84fa59...
==========

[commit-bot: I haz the power, 2016-10-20 17:58:55]

Committed patchset #1 (id:1) as
https://pdfium.googlesource.com/pdfium/+/7403f8a2a0d87179a1ccd57ceccd2d84fa59...