IndexedDB: Replace passing identically-sized vectors with pairs

Avoid the antipattern of passing vectors-that-must-be-the-same-size.
Use a tuple (well, a pair) instead.

R=tsepez@chromium.org,alecflett@chromium.org
BUG=334314

Review URL: https://codereview.chromium.org/138703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245383 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245383
Blink roll 165243:165252

http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=165244:165252&mode=html
TBR=
BUG=

Review URL: https://codereview.chromium.org/141203002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245384 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245385 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245385