Make intl/overrides/caching.js more 'robust'

Bug: None
Test: intl/overrides/caching
Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: Iffd0f58f76d6514924badca18a2112df572e53d2
Reviewed-on: https://chromium-review.googlesource.com/757945Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49334}

test/intl/intl.status

@@ -26,10 +26,6 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 [
-[ALWAYS, {
-  # TODO(jochen): The following test is flaky.
-  'overrides/caching': [PASS, FAIL],
-}],  # ALWAYS
 
 ['variant == wasm_traps', {
   '*': [SKIP],

test/intl/overrides/caching.js

@@ -53,7 +53,9 @@ for (var i = 0; i < 1000; i++) {
 endTime = new Date();
 collatorTime = endTime.getTime() - startTime.getTime();
 
-// Difference is within 20%.
-assertTrue(collatorTime < cachedTime);
+// Difference is within 20%. collatorTime should be smaller,
+// but it can be noisy. Give an enough margin of error.
+assertTrue(collatorTime < cachedTime * 1.5);
 // Non-cached time is much slower, measured to 12.5 times.
 assertTrue(cachedTime < nonCachedTime);
+assertTrue(collatorTime < nonCachedTime);