[gold] byblame-page-sk-demo.js: Make demo page deterministic by faking Date.now.

Bug: skia:9525
Change-Id: Ic0f271b33e5be07268aea6d930e33f813328c625
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/264655
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
diff --git a/golden/modules/byblame-page-sk/byblame-page-sk-demo.js b/golden/modules/byblame-page-sk/byblame-page-sk-demo.js
index 12a2819..283b5f3 100644
--- a/golden/modules/byblame-page-sk/byblame-page-sk-demo.js
+++ b/golden/modules/byblame-page-sk/byblame-page-sk-demo.js
@@ -1,6 +1,13 @@
 import './index.js'
 import '../gold-scaffold-sk'
-import { canvaskit, gm, svg, fakeGitlogRpc, trstatus } from './demo_data'
+import {
+  canvaskit,
+  fakeGitlogRpc,
+  fakeNow,
+  gm,
+  svg,
+  trstatus
+} from './demo_data'
 import { delay } from '../demo_util';
 import { $$ } from 'common-sk/modules/dom'
 import { fetchMock } from 'fetch-mock';
@@ -24,6 +31,8 @@
   return delay(response, fakeRpcDelayMillis);
 }
 
+Date.now = () => fakeNow;
+
 fetchMock.get(
     '/json/byblame?query=source_type%3Dcanvaskit', () => byBlame(canvaskit));
 fetchMock.get('/json/byblame?query=source_type%3Dgm', () => byBlame(gm));
diff --git a/golden/modules/byblame-page-sk/demo_data.js b/golden/modules/byblame-page-sk/demo_data.js
index 6ee6844..01bd001 100644
--- a/golden/modules/byblame-page-sk/demo_data.js
+++ b/golden/modules/byblame-page-sk/demo_data.js
@@ -1,3 +1,5 @@
+export const fakeNow = Date.parse('2019-11-08T00:00:00Z');
+
 export const canvaskit = {
   "data": []
 };