Don't consume into block in ConsumeAttributeReference
The streaming parser does not allow using Consume[IncludingWhitespace]
into a block. Fixed by peeking before consuming.
Fixes crash (DCHECK) for invalid values like "attr(())".
Change-Id: Ic1d26b21d5e82be8375f768b9626cec9e3da375a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5860123
Commit-Queue: Anders Hartvoll Ruud andruud@chromium.org
Reviewed-by: Munira Tursunova moonira@google.com
Cr-Commit-Position: refs/heads/main@{#1355134}