Better handling of progress with streamed files.
Better handling of progress with streamed files.

nmrugg/LZMA-JS,addaleax/LZMA-JS,zzzhan/LZMA-JS,nmrugg/LZMA-JS,zzzhan/LZMA-JS,addaleax/LZMA-JS,nmrugg/LZMA-JS,addaleax/LZMA-JS,zzzhan/LZMA-JS