Optimize ShapeResult::ComputeGlyphBounds

Further optimize ShapeResult::ComputeGlyphBounds by moving population of
source glyphs vector to ComputeGlyphPositions thereby avoiding the extra
iteration over all glyphs in ComputeGlyphBounds. Furthermore by changing
SimpleFontData::BoundsForGlyphs to take a SkRect vector avoids one extra
copy and one extra iteration.

Bug: 591099
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: Ib155ce1e069d5329c5fbc6a8850fc40736ee520b
Reviewed-on: https://chromium-review.googlesource.com/1157271
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579682}
6 files changed