add tolerance for jpeg image length test

Author: etpinard

test/jasmine/tests/toimage_test.js

@@ -160,22 +160,22 @@ describe('Plotly.toImage', function() {
         .then(function() { return Plotly.toImage(gd, {format: 'png', imageDataOnly: true}); })
         .then(function(d) {
             expect(d.indexOf('data:image/')).toBe(-1);
-            expect(d.length).toBeWithin(53660, 1e3);
+            expect(d.length).toBeWithin(53660, 1e3, 'png image length');
         })
         .then(function() { return Plotly.toImage(gd, {format: 'jpeg', imageDataOnly: true}); })
         .then(function(d) {
             expect(d.indexOf('data:image/')).toBe(-1);
-            expect(d.length).toBeWithin(43251, 1e3);
+            expect(d.length).toBeWithin(43251, 5e3, 'jpeg image length');
         })
         .then(function() { return Plotly.toImage(gd, {format: 'svg', imageDataOnly: true}); })
         .then(function(d) {
             expect(d.indexOf('data:image/')).toBe(-1);
-            expect(d.length).toBeWithin(39485, 1e3);
+            expect(d.length).toBeWithin(39485, 1e3, 'svg image length');
         })
         .then(function() { return Plotly.toImage(gd, {format: 'webp', imageDataOnly: true}); })
         .then(function(d) {
             expect(d.indexOf('data:image/')).toBe(-1);
-            expect(d.length).toBeWithin(15831, 1e3);
+            expect(d.length).toBeWithin(15831, 1e3, 'webp image length');
         })
         .catch(fail)
         .then(done);