Pull our new test case repository via deps.

Add a run_corpus_tests.py script to run pdfium_test against
the corpus tree.

Note that this differs from the run_pixel_tests.py script,
since pre-processing is not required.  I'll work on unifying
these in a subsequent CL.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1010833003
2 files changed