RunningBlock 的两个bug：设置speed崩溃、控件整体尺寸变化时不会刷新滚动 #901

Describe the bug
1、当设置speed的时候，会弹出错误
2、在外框尺寸发生变化的时候不会UpdateContent

To Reproduce
Steps to reproduce the behavior:
1、代码：

<hc:RunningBlock
    Width="100"
    Margin="0,16,0,0"
    HorizontalAlignment="Left"
    AutoReverse="True"
    AutoRun="True"
    Content="test test test test test test test test test test"
    Runaway="False"
    Speed="200" />

当runaway为false的时候设置speed会崩溃，应该是UpdateContent的TimeSpan.FromSeconds((to-from)/Speed)这里to-from为负导致

2、window中只放置

<hc:RunningBlock
  Margin="0,16,0,0"
  HorizontalAlignment="Stretch"
  VerticalAlignment="Top"
  AutoReverse="True"
  AutoRun="True"
  Content="test test test test test test test test test test"
  Runaway="False" />

拖动缩放window的时候滚动状态不会改变
期望当autorun=True的时候，如果整体尺寸发生变化，也会刷新是否开始滚动
建议在RunningBlock的SizeChange中也添加UpdateContent

Environment (please complete the following information):

• .net: [e.g. 4.5.2]
• IDE [e.g. vs2019]
• Version [e.g. 3.2.0]