Early object closing in PDF via premature 'endobj' keyword

Adobe acrobat defines keywords "\nendstream\n" and "\nendobj\n" in object's stream.
However, Pdfium searches "endstream" and "endobj" as the keywords in the streams of objects.
Some words like "(endstream)" are wrongly treated as keywords in pdfium.
This fix follows Adobe's solution.

BUG=493126
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1219133005 .
2 files changed