To help web authors diagnose why QuotaExceededError occurred on local repros, let's add something to chrome://media-internals when QuotaExceededError results from appendBuffer attempt.

The message would ideally at least contain the exception message, the number of bytes attempted to be appended, the number of bytes currently in (each of) the buffered tracks before and after the GC heuristic ran.

We should also include this additional detail in the actual QuotaExceededError, which currently is just "The SourceBuffer is full, and cannot free space to append additional buffers." This would allow web authors aggregate errors to help with debugging hard-to-repro cases.