[testing docs] Fix web test link

Change-Id: If88a9f663337ee91aee816459e9f4ae35ebaaaec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1810184
Commit-Queue: Annie Sullivan <sullivan@chromium.org>
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697652}

docs/speed/benchmark/harnesses/blink_perf.md

@@ -5,7 +5,7 @@
 ## Overview
 
 Blink perf tests are used for micro benchmarking the surface of Blink that
-is exposed to the Web. They are the counterpart of [web_tests/](../../../docs/testing/layout_tests.md)
+is exposed to the Web. They are the counterpart of [web_tests/](../../../testing/web_tests.md)
 but for performance coverage.
 
 ## Writing Tests