The type of the performance entry. It may be one of:
'node' (Node.js only)
'node'
'mark' (available on the Web)
'mark'
'measure' (available on the Web)
'measure'
'gc' (Node.js only)
'gc'
'function' (Node.js only)
'function'
'http2' (Node.js only)
'http2'
'http' (Node.js only)
'http'
v8.5.0