StyleSheet.title should return null for empty string titles
According to https://drafts.csswg.org/cssom/#dom-stylesheet-title
an empty title should return null. We do so for the html style element,
but not for link elements or constructed stylesheets.
Bug: 40680935
Change-Id: I43ae1795e66b29f2b90630e7cd419bbf47e03998
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5741590
Reviewed-by: Rune Lillesveen futhark@chromium.org
Reviewed-by: Daniil Sakhapov sakhapov@chromium.org
Commit-Queue: Daniil Sakhapov sakhapov@chromium.org
Cr-Commit-Position: refs/heads/main@{#1337285}