The constant for the return sequence length (JSReturnSequenceLength) was
defined in debug.h. Since this constant are also needed outside the debugger code
I moved them into assembler-xxx.h. Otherwise compiling with debuggersupport=off
would fail on ARM.

BUG=http://code.google.com/p/v8/issues/detail?id=533

Review URL: http://codereview.chromium.org/456001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3383 ce2b1a6d-e550-0410-aec6-3dcde31c8c00