Stats example uses confusing variable names

[henbos]

https://w3c.github.io/webrtc-stats/#example-of-a-stats-application uses variable names that refer to both RTCStats (report) and RTCStatsReport (currentReport) as reports.

Clearly one is a report and one is a stats object. The former is clearly a report and the latter, well up for debate if this should be called stat or stats or statsObject. I don't really care as long as we don't call it a report.

Normally I wouldn't care that this example is using silly variable names, but apparently we have duplicated this confusion to both samples and CLs.