Fix segv in CPDF_DataAvail::CheckRoot() when /Root object is a string.

Fix segv in CPDF_DataAvail::CheckRoot() when /Root object is a string.

Handles the case of this malformed PDF without crashing. Note that to
get a reproducible test case, a small fix is applied to our .py script
which results in some whitespace/numbering difs across the resources
(down the road, we ought to generate them on the fly in an intermediate
directory).

BUG=454695
R=jun_fang@foxitsoftware.com, thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/219b3dab7e184bf8742f61527e37053b04903ff0

[Tom Sepez, 2015-02-03 20:35:44]

tsepez@chromium.org changed reviewers:
+ jun_fang@foxitsoftware.com, thestig@chromium.org

[Tom Sepez, 2015-02-03 20:35:45]

Lei, Jun, please review.

[jun_fang, 2015-02-03 23:20:20]

On 2015/02/03 20:35:45, Tom Sepez wrote:
> Lei, Jun, please review.

LGTM

[Tom Sepez, 2015-02-05 18:31:21]

Lei, you want to take a quick look before I land this? Thanks.

[Lei Zhang, 2015-02-05 18:35:28]

You probably need to resolve merge conflicts, but lgtm.

[Tom Sepez, 2015-02-05 18:40:35]

New patchsets have been uploaded after l-g-t-m from
jun_fang@foxitsoftware.com,thestig@chromium.org

[Tom Sepez, 2015-02-05 18:41:12]

Committed patchset #3 (id:40001) manually as
219b3dab7e184bf8742f61527e37053b04903ff0 (presubmit successful).