Add definition of ENABLE_DEBUGGER_SUPPORT to v8 gyp file.

This reflects the change in r2875 (http://code.google.com/p/v8/source/detail?r=2875) where ENABLE_DEBUGGER_SUPPORT is not longer defined automatcally in v8.h.
Review URL: http://codereview.chromium.org/196120

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2883 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/gyp/v8.gyp

@@ -40,6 +40,7 @@
   'target_defaults': {
     'defines': [
       'ENABLE_LOGGING_AND_PROFILING',
+      'ENABLE_DEBUGGER_SUPPORT',
     ],
     'conditions': [
       ['target_arch=="arm"', {