LayoutLib: When possible ensure parsers are popped from the stack.

Some parser consumers (seems to be mostly resource inflation)
don't use the pull parser up to the END_DOCUMENT tag, making
the parser not pop itself from the parser stack automatically.

This is likely due to the XML resources being very shallow (1-2 levels
max), and the inflater just reading the content that it expects instead
of parsing till the document is done.

This ensures that *some* parsers are pop'ed from the stack when
used. Some other parsers we don't really control and hope the
user will parse till END_DOCUMENT.

Change-Id: Ie1f5762983fed2b2ae97b896218ae12b493e7ad9