[LayoutNG] Fix PDI/PDF not to affect line breaking

This patch fixes PDI/PDF before spaces not to suppress the
line breaking opportunity at the space. For example, before
this fix, `<bdo dir=ltr>a</bdo> b` could not break between
"a" and "b".

PDI and PDF are injected by the `unicode-bidi` property, or
elements that imply the `unicode-bidi` property such as
`<bdi>`, `<bdo>`, or any elements with `dir` attributes.

Bug: 989094
Change-Id: I2128774e2b062ecb86880812c54d46299a19a18a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1735146
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683881}
2 files changed