[Android] Fix that dict.iteritems() is no longer supported in python 3.0+

'dict' object has no attribute 'iteritems' in python 3.0 and later,
use dict.items() instead.

BUG=https://crosswalk-project.org/jira/browse/XWALK-2129
Merge pull request #2213 from jinbang/fix_dict_iteritems

[Android] Fix that dict.iteritems() is no longer supported in python 3.0...