Oilpan: Add a comment to markPointer
Oilpan: Add a comment to markPointer

To clarify when we hit the 'gcInfo->hasVTable() && !vTableInitialized(header->payload())' branch.

BUG=474470

Review URL: https://codereview.chromium.org/1084463004

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@194364 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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