Blob not defined in IE9 strict mode

[stephenliberty]

Our javascript files are compiled with a "use strict" header. Unfortunately that seems to cause an error in the file at line 175 where there is a check to see if the srcImage is an instance of a Blob. Since Blob isn't defined, the script proceeds to error out.

The quick fix, which seems as though it works, is to check to see if window.Blob exists prior to checking to see if it's an instance of said Blob.

if (window.Blob && srcImage instanceof Blob) {

[stomita]

Thanks. I'll update this when I'm free. If you can't wait, pull request is welcome.