1. This policy was only used for unused spill operands. I'm assigning
an INVALID LOperand to those instead. As a result, we only need
3 bits to encode the policy and have one more available for virtual
registers.

2. Furthermore, corrected the calculation of the maximal number of virtual
registers and changed the upper limit for the size of the Hydrogen IR
accordingly.

3. Doubled the maximal number of deoptimization entries to 8K.
Review URL: http://codereview.chromium.org/9160018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10481 ce2b1a6d-e550-0410-aec6-3dcde31c8c00