Allow bailing out of the register allocator when running out of virtual registers.

Allow bailing out of the register allocator when running out of virtual registers.

1. Instead of checking upfront and estimating a limit for the number, we
now are able to stop register allocation and bailout when we don't
have enough virtual registers.

2. GCed some out-dated flags from flag-definition.h

3. Simplified the interface from the Lithium builder to the
register allocator in lithium-*.cc: For uses and definitions, we
just record the virtual register number given by the Hydrogen value id.
For temporaries, we request a new virtual register from the allocator.
For fixed temps, we don't need to do anything.

4. Increased number of deoptimization entries to 16K. Eventually we
probably want to make this array grow dynamically.
Review URL: https://chromiumcodereview.appspot.com/9325019

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10597 ce2b1a6d-e550-0410-aec6-3dcde31c8c00