Skip unnecessary measurements when possible

This change introduces a new measure cache to View, to remember
the measured dimensions for previous pairs of measure specs. The
measure cache is cleared whenever a View requests layout.

Unfortunately some Views rely on measure being always called when
layout is invoked. To work around this problem, we need to remember
when we hit the measure cache to force a call to measure just prior
to calling onLayout(). This does not completely removes all measure
calls but enough to optimize a number of layouts.

Change-Id: Ie085fbcf186e9d7505e1127e0786a12968ebc344