Enables cross-compilation of the VM for ARM.

runtime/third_party/double-conversion/src/double-conversion.gypi

 # Copyright 2010 Google Inc. All Rights Reserved.
 
 {
   'targets': [
     {
       'target_name': 'libdouble_conversion',
       'type': 'static_library',
+      'toolsets':['target','host'],
       'dependencies': [
       ],
       'include_dirs': [
         '.',
       ],
       'sources': [
         'bignum.cc',
         'bignum.h',
         'bignum-dtoa.cc',
         'bignum-dtoa.h',
         'cached-powers.cc',
         'cached-powers.h',
         'diy-fp.cc',
         'diy-fp.h',
         'double.h',
         'double-conversion.cc',
         'double-conversion.h',
         'fast-dtoa.cc',
         'fast-dtoa.h',
         'fixed-dtoa.cc',
         'fixed-dtoa.h',
         'strtod.cc',
         'strtod.h',
         'utils.h',
       ],
     },
   ],
 }