Revert "Disable ResultDB for test_runner.py on Windows"

This reverts commit 3deb8857c5057c171f89369a41fb2aeb4192ce2e.

Reason for revert: Fixed by crrev.com/c/3958475

Original change's description:
> Disable ResultDB for test_runner.py on Windows
>
> Temporarily disables ResultDB reporting for test_runner.py tests on
> Windows. These tests run much slower in this configuration, and we're
> still investigating why.
>
> Bug: pdfium:1921
> Change-Id: I24b7285a9750f11745fcdaaef60c5aeaf195d719
> Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/99374
> Commit-Queue: Lei Zhang <thestig@chromium.org>
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Auto-Submit: K. Moon <kmoon@chromium.org>
> Commit-Queue: K. Moon <kmoon@chromium.org>

Change-Id: I8dec3d7d321e761a8ec8611b06f6fd47911aabf4
Fixed: pdfium:1921
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/99470
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: K. Moon <kmoon@chromium.org>
diff --git a/testing/tools/test_runner.py b/testing/tools/test_runner.py
index 2c61745..b1b1986 100644
--- a/testing/tools/test_runner.py
+++ b/testing/tools/test_runner.py
@@ -10,7 +10,6 @@
 from dataclasses import dataclass
 import multiprocessing
 import os
-import platform
 import re
 import shutil
 import subprocess
@@ -433,11 +432,6 @@
     if self.resultdb:
       print('Detected ResultSink environment')
 
-      # TODO(crbug.com/pdfium/1921): Fix performance on Windows.
-      if platform.system() == 'Windows':
-        self.resultdb = None
-        print('Disabled ResultDB support due to https://crbug.com/pdfium/1921')
-
     # Collect test cases.
     walk_from_dir = finder.TestingDir(relative_test_dir)