Make performance.now behave more like real world

Author: njourdain

projects/ng-dev/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@sama/ng-dev",
-  "version": "20.0.0",
+  "version": "20.0.1",
   "author": "Samasource",
   "license": "MIT",
   "homepage": "https://github.com/Samasource/s-libs/tree/master/projects/ng-dev",

projects/ng-dev/src/lib/angular-context/angular-context.ts

@@ -260,7 +260,9 @@ export class AngularContext {
   #runWithMockedTime(test: VoidFunction): void {
     // https://github.com/angular/angular/issues/31677#issuecomment-573139551
     const { now } = performance;
-    spyOn(performance, 'now').and.callFake(() => Date.now());
+    spyOn(performance, 'now').and.callFake(
+      () => Date.now() - this.startTime.getTime(),
+    );
 
     jasmine.clock().install();
     fakeAsync(() => {