Clean up _getFileExtension() method and fix all its callers
fixed unnecessary escaping
+fixes
getLastIndexOf > lastIndexOf
- unnecessary var decl
Merge branch 'master' into jeff/pr4846
Final changes to code review needed to get this into sprint 31
Merge pull request #5224 from adobe/jeff/pr4846

Clean up _getFileExtension() method and fix all its callers