Invalidation not taking glyph bounds into account on HarfBuzz path

Implement support for computing and populating the GlyphOverflow
structure for the harfbuzz code path. The current implementation is a
straight copy of the current Mac implementation with minor
modifications to use the corresponding harfbuzz APIs.

R=dglazkov@chromium.org,behdad@chromium.org
BUG=354165
TEST=fast/text/international/repaint-glyph-bounds.html

Review URL: https://codereview.chromium.org/205553003

git-svn-id: svn://svn.chromium.org/blink/trunk@169605 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove dead code for dragging MediaControlPanelElement

Because setCanBeDragged(true) is never called, all the rest of the
dragging code becomes unreachable. The feature as such looks useful, but
it would require fixing and above all testing to interact well with text
track rendering.

BUG=341813
TEST=LayoutTests/media/ still passes, i.e. there were none!

Review URL: https://codereview.chromium.org/196533020

git-svn-id: svn://svn.chromium.org/blink/trunk@169606 bbb929c8-8fbe-4397-9dbb-9b2b20218538