This adds a new timeline renderer using a plain canvas element,
replacing the d3 and svg-based renderer. This new implementation
greatly improves timeline performance, especially on less powerful
graphics cards, and more than doubles the resulting framerate while
panning the view by aggressively caching previously rendered chart
regions. Additionally, worst-case memory usage is greatly reduced
during heavier periods of user interaction.
This new implementation also removes several previous limitations.
Due to cached rendering a nearly unlimited number of objects can be
shown at any time with no performance impact, so small objects never
need to be hidden from view at any zoom level. Also, view transitions
can now be smoothly animated, and reach a stable framerate even on
older mobile devices.
Change-Id: Ib883e056270eff688b4b4a0c340eaea20cceb181
72a3317656