Add a check to presubmit.py linting python and SCons files for trailing white...

SConstruct

 # Copyright 2008 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 620 matching lines @@
     if match:
       version_components.append(match.group(1).strip())
     else:
       version_components.append('0')
 
   return version_components
 
 
 def GetVersion():
   version_components = GetVersionComponents()
-  
+
   if version_components[len(version_components) - 1] == '0':
     version_components.pop()
   return '.'.join(version_components)
 
 
 def GetSpecificSONAME():
   SONAME_PATTERN = re.compile(r"#define\s+SONAME\s+\"(.*)\"")
-  
+
   source = open(join(root_dir, 'src', 'version.cc')).read()
   match = SONAME_PATTERN.search(source)
-  
+
   if match:
     return match.group(1).strip()
   else:
     return ''
 
 
 def SplitList(str):
   return [ s for s in str.split(",") if len(s) > 0 ]
 
 
@@ skipping 260 matching lines @@
 # version of scons.  Also, there's a bug in some revisions that
 # doesn't allow this flag to be set, so we swallow any exceptions.
 # Lovely.
 try:
   SetOption('warn', 'no-deprecated')
 except:
   pass
 
 
 Build()