test: fix incorrect calculation in test-perf-hooks.js

After https://redirect.github.com/nodejs/node/pull/46588,
Date.now() - performance.timeOrigin and process.uptime()
are no longer similar - the former measures uptime from
process initilaization, while the latter measures uptime from
the main context initialization. Account for the differences
in the test.

Author: joyeecheung

test/sequential/test-perf-hooks.js

@@ -28,15 +28,10 @@ const epsilon = 50;
 {
   const uptime1 = Date.now() - performance.timeOrigin;
   const uptime2 = performance.now();
-  const uptime3 = process.uptime() * 1000;
   assert(Math.abs(uptime1 - uptime2) < epsilon,
          `Date.now() - performance.timeOrigin (${uptime1}) - ` +
          `performance.now() (${uptime2}) = ` +
          `${uptime1 - uptime2} >= +- ${epsilon}`);
-  assert(Math.abs(uptime1 - uptime3) < epsilon,
-         `Date.now() - performance.timeOrigin (${uptime1}) - ` +
-         `process.uptime() * 1000 (${uptime3}) = ` +
-         `${uptime1 - uptime3} >= +- ${epsilon}`);
 }
 
 assert.strictEqual(performance.nodeTiming.name, 'node');
@@ -93,6 +88,18 @@ checkNodeTiming(initialTiming);
   assert(nodeStart < testStartTime,
          `nodeStart ${nodeStart} >= ${testStartTime}`);
 
+  {
+    // Due to https://github.com/nodejs/node/pull/46588,
+    // The difference between process.uptime() and (Date.now() - performance.timeOrigin)
+    // is roughly performance.nodeTiming.nodeStart
+    const uptime1 = Date.now() - performance.timeOrigin;  // now - process start time
+    const uptime3 = process.uptime() * 1000;  // now - node start time
+    assert(Math.abs(uptime1 - uptime3 - nodeStart) < epsilon,
+          `Date.now() - performance.timeOrigin (${uptime1}) - ` +
+          `process.uptime() * 1000 (${uptime3}) = ` +
+          `${uptime1 - uptime3} >= +- ${epsilon}`);
+  }
+
   assert.strictEqual(typeof v8Start, 'number');
   assert(v8Start > 0, `v8Start ${v8Start} <= 0`);
   // V8 starts after the process starts.