Fix live seek bar on touch screens
Fix live seek bar on touch screens

The UI seek bar on touch screen devices was broken in PR #2036 and
v2.5.4 - v2.5.11 for live content.  VOD content, which starts at 0,
was unaffected.

This fixes the range calculations for touch events to correctly
account for the minimum seek range.

Closes #2558

Change-Id: Ic3f6230d88703fd0ea1c9bc15057c0656b1dc42f

shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player