Optimize drawHardwareAccelerated method in Editor class

When inserting a new line or breaking a line,
every display list was invalidated and rebuilt before.
However, we can reuse the display lists above intactly and also
reuse the display lists below with only updating drawing locations.

This patch reuses the display lists if possible.
The display lists above the inserted line are just reused
and the display lists below are reused with only updating
drawing locations not fullly rebuilt.

mIndexOfFirstChangedBlock is the index of the first block
which is moved by inserting or breaking a line.
So the display list whose index is >= mIndexOfFirstChangedBlock
only needs to update its drawing location.

Change-Id: Ica20deb0ebb5750de21356ed31fa9f86e657ff92
Signed-off-by: Sangkyu Lee <sk82.lee@lge.com>