Attach whitespaces to the neighbor unresolved blocks

Fix the situation when an unresolved {arabic} text is broken into
many small runs by resolved english spaces.

Bug: skia:10487
Change-Id: I3a739501c0fb7e0fc845e68392e1d214df9302db
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/304000
Commit-Queue: Julia Lavrova <jlavrova@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
4 files changed