Always redraw text that protrude from line bounds.

With I63af3a6ecbf92, we create RenderNode lazily, but
blocks containing contents that protrude from line top or
bottom cannot be simply lazily redrawn after edit or
scroll.
With this CL, we check if the contents protrude from line
top or bottom by comparing the text bounds with relevant
font metrics values and we always redrawn such blocks after
edit or scroll.

Bug: 27889485
Change-Id: I666da5eeb39f780c341597f347bfcba21eb34295