Although algorithmically correct, the compiler would not allow to instantiate
a BitField that uses all 32 bits without warnings about a too large shift
count. As a consequence we were limited to 31 bit values when using BitField.

This happened when instantiating a bitfield BitField<T, shift, size> with 
[shift=0, size=32] or [shift=31, size=1] or more general any 
[shift=X, size=32-X]

As side-effect of the new implementation the compiler now warns if we ever
try instantiating a bitfield with size 0.

Review URL: http://codereview.chromium.org/606063

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3910 ce2b1a6d-e550-0410-aec6-3dcde31c8c00