Win: Fix printing selected pages with native dialog.

During the PDF to EMF conversion process, the converter only knows a
page as the Nth page of the PDF, and no longer has the original page
number. Remember the association, so the Windows printing code can
figure out the actual page number after the conversion finishes.

Fix nits and typos along the way.

BUG=553446

Review-Url: https://codereview.chromium.org/2271743003
Cr-Commit-Position: refs/heads/master@{#414081}
3 files changed