Localized optimizations in views and bitmaps

* Don't call context.getResources() redundantly when unnecessary;
  similarly for Resources.getCompatibilityInfo()

* During bitmap creation, don't bother clearing to 0: it's unnecessary
  because now that the raw bits are stored in a VM-side byte array, it
  was cleared at initialization time.  Also, don't use the sanity-
  checking public entry point to erase to a color, because we know
  that we're by definition in a "legal" path to erase to the initial
  contents and don't need to incur the overhead of the (inappropriate)
  sanity checking.

Change-Id: Idaca4d64fdecefd5d51337646ead32e1db510e02