This patch
- removes the unimplemented code crash when rendering invalid/unknown instructions and prints "unknown" instead.
- prints the beginning of the constant pool marker.
- adds "da" as a shortcut for "disasm".
- print hexadecimal representation of double and single registers. This makes it easier to debug move/conversion code that uses temporary int32 values in floating point registers.
- annotates the stack with short prints of the values (HeapObjects and smis),
- makes disasm take an address or a register as second argument without a third argument, which defaults to printing ten instructions.

Review URL: http://codereview.chromium.org/6676042

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7279 ce2b1a6d-e550-0410-aec6-3dcde31c8c00