Fix nested cross-scrolling for ScrollView/HorizontalScrollView

Bug 6429006

Disallow intercepting touch events for parents of
ScrollView/HorizontalScrollView when scrolling begins. Properly
respect touch slop when the child of a ScrollView does not accept
touch events.

Change-Id: I2ce503ad5104d450829ed58cd2748c9163e020d3
2 files changed