Revert of IndexedDB: Don't timeout read-only transactions

Revert of IndexedDB: Don't timeout read-only transactions (https://codereview.chromium.org/180163010/)

Reason for revert:
Break Chromium Memory on Linux ASan+LSan Tests (2)

http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%2BLSan%20Tests%20%282%29/builds/65/steps/content_unittests/logs/NoTimeoutReadOnly

Original issue's description:
> IndexedDB: Don't timeout read-only transactions
> 
> Chrome introduced a transaction timeout to deal with potentially wedged
> renderers (e.g. JS execution halted, etc) failing to complete transactions,
> leaving the browser's transaction queue in a bad state. This was done
> for all transactions, but since read-only transactions don't hold up
> the queue it's safe to ignore them, which can reduce false-positives.
> 
> BUG=339229
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=254846

TBR=dgrogan@chromium.org,cmumford@chromium.org,jsbell@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=339229
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=254868

[stgao, 2014-03-04 22:59:23]

Created Revert of IndexedDB: Don't timeout read-only transactions

[commit-bot: I haz the power, 2014-03-04 23:00:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/stgao@chromium.org/185403019/1

[commit-bot: I haz the power, 2014-03-04 23:02:37]

Change committed as 254868