util: Fix build of LinkNode.java.

If you compile with JDK 1.7 you get the following error:

mNext has private access in LinkedNode
return T node.mNext == mHead ? null : node.mNext;

Change-Id: Ic1e60f76461da3e75b4ca8402622251e63569beb
Make the overscroll color match Kitkat

Switch from holo blue to white/grey like the rest of Kitkat.

Change-Id: Id2f8393aead5b5128cd3e906cf8bea84692601d1