Previously, we were referencing the mixpanel objects only once, at
page load time, which meant that there was a race between metrics.js
loading and mixpanel completely loading. Mixpanel starts with stub
methods and then replaces them once it fully loads, asynchronously.
If metrics.js ran before mixpanel loaded, we'd end up wrapping the
stub methods instead of the real versions. Adding a layer of
indirection ensures that we always get the right method.
(imported from commit 6a8cfbf249168443956895b7a7e29bf7bb4222aa)
Currently, some browsers don't seem to be sending metrics information
to mixpanel. This commit will make said browsers noisy, but should
help debug what's going on.
(imported from commit c5050f66d985eb76e38117b2668594fedfc10702)
Zev Benjamin