Fallback UI is no longer kicked on error after #2719

[vyv03354]

http://www.devk.de/media/content/download/produkte/hauswohnen/DEVK-Glas-Produktinfo-08507-303-2011-09.pdf
displayed the infobar before #2719.
Moreover, the error message is much less informative.
0.8.49:

[02:23:30.538] "An error occurred while rendering the page.
PDF.js v0.8.47 (build: added3d)
Message: JPEG error: Unsupported color mode
Stack: error@resource://pdf.js/build/pdf.js:761
JpegStream_ensureBuffer@resource://pdf.js/build/pdf.js:31861
DecodeStream_getBytes@resource://pdf.js/build/pdf.js:31144
PDFImage_getImageBytes@resource://pdf.js/build/pdf.js:27019
PDFImage_fillRgbaBuffer@resource://pdf.js/build/pdf.js:26953
PDFImage_getImageData@resource://pdf.js/build/pdf.js:27014
pdfjsWrapper/PartialEvaluator_getOperatorList/buildPaintImageXObject/<@resource://pdf.js/build/pdf.js:14465
pdfjsWrapper/PDFImage_buildImage/<@resource://pdf.js/build/pdf.js:26697
Promise_resolve@resource://pdf.js/build/pdf.js:1361
pdfjsWrapper/Promise_all/<@resource://pdf.js/build/pdf.js:1308
Promise_resolve@resource://pdf.js/build/pdf.js:1361
PDFImage_buildImage@resource://pdf.js/build/pdf.js:26720
buildPaintImageXObject@resource://pdf.js/build/pdf.js:14467
PartialEvaluator_getOperatorList@resource://pdf.js/build/pdf.js:14587
Page_getOperatorList@resource://pdf.js/build/pdf.js:240
wphSetupRenderPage@resource://pdf.js/build/pdf.js:33603
messageHandlerComObjOnMessage@resource://pdf.js/build/pdf.js:33420
"
[02:23:37.228] Error: Unknown compression method in flate stream: 236, 207 @ resource://pdf.js/build/pdf.js:761

0.8.61:

[02:24:14.419] Error: JPEG error: Unsupported color mode @ resource://pdf.js/build/pdf.js:1377

[yurydelendik]

Fixed by #3229