downloads in "full-json" produce filename with .json extension

Author: antoinerg

src/snapshot/download.js

@@ -51,7 +51,7 @@ function downloadImage(gd, opts) {
         var promise = toImage(gd, opts);
 
         var filename = opts.filename || gd.fn || 'newplot';
-        filename += '.' + opts.format;
+        filename += '.' + opts.format.replace('-', '.');
 
         promise.then(function(result) {
             if(_gd) _gd._snapshotInProgress = false;

test/jasmine/tests/download_test.js

@@ -209,7 +209,7 @@ function downloadTest(gd, format) {
         var linkdeleted = domchanges[domchanges.length - 1].removedNodes[0];
 
         expect(linkadded.getAttribute('href').split(':')[0]).toBe('blob');
-        expect(filename).toBe('plotly_download.' + format);
+        expect(filename).toBe('plotly_download.' + format.replace('-', '.'));
         expect(linkadded).toBe(linkdeleted);
     });
 }