Themes: Fix blurry composed icons

In a composed icon the original icon could be scaled incorrectly
due to a density mismatch resulting in blurry icons.

For example, Grouper has a screen density of 213 dpi but Trebuchet will want to show a larger icon and therefore
requests to the framework to load app icons with a slightly higher density of 320dpi (XHDPI bucket).

When Resources.loadDrawable(TypedValue value, ...) is called, it will use observe value.density. Since the image
is from the XHDPI bucket it will have a TypedValue.density of 320dpi, much higher than the screen's 213dpi, and therefore
loadDrawablei() will configure BitmapFactory to scale down the image to match the screen density. This is not what we want,
so this patch modifies the density value to prevent scaling, much the same way getDrawableForDensity() does.

Change-Id: Ie638c8576872f9115dc029bb4823b50bb31ecebf
Themes: Load missing style attributes from original style

If a theme overrides a style in an app and does not include all
the attributes found in the original, it is possible for the app
to crash because it cannot locate an attribute it is expecting.

To overcome this we need to check the attributes in the original
style's bag and add any missing attributes to the current bag being
populated.  Currently we have only seen one theme that causes this
behavior, but there could be others out there or we may eventually
see this happen in the wild as apps update and the themes have not
had a chance to incorporate the new additions from the app.

Change-Id: Id44aa83a6c58a0b042d2b32171bed5e794352670