Use count is way too high, hence gathering more stats

 issue 689601  and https://codereview.chromium.org/2683333002

From the CL:

The "legacy" prefixed quota APIs have ridiculously high usage counts:

The oldest one window.webkitStorageInfo tracked as PrefixedStorageInfo
has 0.07% of page loads which is crazy high...

But navigator.webkitTemporaryStorage/webkitTemporaryStorage tracked
together as as PrefixedStorageQuota have 0.8% of page loads!

The counters exist on the attributes gating access, rather than the
methods themselves, so they might be getting overcounted due to
simple enumeration of the window/navigator objects.

Looking at the Canary data (14 day aggregation):

V8DeprecatedStorageInfo_QueryUsageAndQuota_Method   00.00%
V8DeprecatedStorageInfo_RequestQuota_Method         00.00%
V8DeprecatedStorageQuota_QueryUsageAndQuota_Method  00.01%
V8DeprecatedStorageQuota_RequestQuota_Method        00.00%

The 0% ones have very low absolute numbers. The 0.01% one has a legitimately high number. So... optimistic we will be able to remove webkitStorageInfo but we'll need to wait for the counters to hit stable.