Revert "Optimize ShapeResult::ComputeGlyphBounds"

This reverts r579682 (commit a5d5bb89a464f812803f6b5b6a2feb9f656f52eb).
Reason for revert: Caused regression for RTL text.

Bug: 870178, 591099
Tbr: kojii@chromium.org
Change-Id: Ic8d79c86c59d649636d065a697b11d37f029efe7
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Reviewed-on: https://chromium-review.googlesource.com/1166298
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581427}
6 files changed