[LayoutNG] Implement line height from font metrics when elements wraps

When elements wraps, 'line-height: normal' should take used fonts of
each line into account, but it was talking used fonts of the element
instead. This patch implements this case using the ShapeResult from

This patch also fixes a case where ShapeResult was not set.


Change-Id: Idf11e7b4676ec0639aa3ffa94890619502064070
Reviewed-on: https://chromium-review.googlesource.com/572603
Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487110}
6 files changed