doc: fixup perf_hooks

doc/api/perf_hooks.md

@@ -55,7 +55,9 @@ Performance Timeline. If `name` is provided, removes only the named mark.
 
 ### `performance.eventLoopUtilization([utilization1[, utilization2]])`
 <!-- YAML
-added: v14.10.0
+added:
+ - v14.10.0
+ - v12.19.0
 -->
 
 * `utilization1` {Object} The result of a previous call to
@@ -222,62 +224,6 @@ obs.observe({ entryTypes: ['function'] });
 wrapped();
 ```
 
-### `performance.eventLoopUtilization([util1][,util2])`
-<!-- YAML
-added: v12.19.0
--->
-
-* `util1` {Object} The result of a previous call to `eventLoopUtilization()`
-* `util2` {Object} The result of a previous call to `eventLoopUtilization()`
-    prior to `util1`
-* Returns {Object}
-  * `idle` {number}
-  * `active` {number}
-  * `utilization` {number}
-
-The `eventLoopUtilization()` method returns an object that contains the
-cumulative duration of time the event loop has been both idle and active as a
-high resolution milliseconds timer. The `utilization` value is the calculated
-Event Loop Utilization (ELU). If bootstrapping has not yet finished, the
-properties have the value of 0.
-
-`util1` and `util2` are optional parameters.
-
-If `util1` is passed then the delta between the current call's `active` and
-`idle` times are calculated and returned (similar to [`process.hrtime()`][]).
-Likewise the adjusted `utilization` value is calculated.
-
-If `util1` and `util2` are both passed then the calculation adjustments are
-done between the two arguments. This is a convenience option because unlike
-[`process.hrtime()`][] additional work is done to calculate the ELU.
-
-ELU is similar to CPU utilization except that it is calculated using high
-precision wall-clock time. It represents the percentage of time the event loop
-has spent outside the event loop's event provider (e.g. `epoll_wait`). No other
-CPU idle time is taken into consideration. The following is an example of how
-a mostly idle process will have a high ELU.
-
-<!-- eslint-skip -->
-```js
-'use strict';
-const { eventLoopUtilization } = require('perf_hooks').performance;
-const { spawnSync } = require('child_process');
-
-setImmediate(() => {
-  const elu = eventLoopUtilization();
-  spawnSync('sleep', ['5']);
-  console.log(eventLoopUtilization(elu).utilization);
-});
-```
-
-While the CPU is mostly idle while running this script the value of
-`utilization` is 1. This is because the call to [`child_process.spawnSync()`][]
-blocks the event loop from proceeding.
-
-Passing in a user-defined object instead of the result of a previous call to
-`eventLoopUtilization()` will lead to undefined behavior. The return values
-are not guaranteed to reflect any correct state of the event loop.
-
 ## Class: `PerformanceEntry`
 <!-- YAML
 added: v8.5.0
@@ -405,7 +351,9 @@ initialized.
 
 ### `performanceNodeTiming.idleTime`
 <!-- YAML
-added: v14.10.0
+added:
+  - v14.10.0
+  - v12.19.0
 -->
 
 * {number}
@@ -458,19 +406,6 @@ added: v8.5.0
 The high resolution millisecond timestamp at which the V8 platform was
 initialized.
 
-### `performanceNodeTiming.idleTime`
-<!-- YAML
-added: v12.19.0
--->
-
-* {number}
-
-The high resolution millisecond timestamp of the amount of time the event loop
-has been idle within the event loop's event provider (e.g. `epoll_wait`). This
-does not take CPU usage into consideration. If the event loop has not yet
-started (e.g., in the first tick of the main script), the property has the
-value of 0.
-
 ## Class: `perf_hooks.PerformanceObserver`
 
 ### `new PerformanceObserver(callback)`