record static method
Records an elapsed micros span under name.
Only call from inside an if (D4rtProfiler.enabled) guard so it is
dead-code-eliminated when the profiler is off.
Implementation
static void record(String name, int micros) {
var entry = _entries[name];
if (entry == null) {
entry = _ProfileEntry(name);
_entries[name] = entry;
_order.add(name);
}
entry.totalMicros += micros;
entry.count++;
}