Use WebURL parameter type for storagePartition in queryStorageUsageAndQuota

It'd be clearer since the callee side (chrome) uses the given parameter as GURL.

BUG=259660
TEST=no behavioral change

Review URL: https://chromiumcodereview.appspot.com/19774002

git-svn-id: svn://svn.chromium.org/blink/trunk@154622 bbb929c8-8fbe-4397-9dbb-9b2b20218538