Prevent the loadingBar from overlaying the errorWrapper
Split files into worker and main thread pieces.
[CRX] Fixes to view local files again

pdfHandler-local.js references the isPdfDownloadable function from
pdfHandler.js, but the function didn't expect that the responseHeaders
property was absent. Added a check to prevent a runtime error when a
local file is displayed in a frame, and show local PDF files again.

Local files are rendered on the chrome-extension:-protocol. The previous
method of getting the PDF URL was incorrect, this has been fixed as well.
Show sensible output for showText commands in the stepper.
Don't provide optional pushState parameter
Merge pull request #3530 from brendandahl/worker-split

Split files into worker and main thread pieces.
Merge remote-tracking branch 'mozilla/master' into pushState
IE9 does not need onreadystatechange
Enable loading of PDFs with undefined or missing stream lengths
Merge pull request #3581 from yurydelendik/pushState

Misc IE fixes
Adds initial telemetry probes
Specifies default workerSrc (if possible)
Merge pull request #3575 from brendandahl/text-debugger

Show sensible output for showText commands in the stepper.
Merge pull request #3519 from Snuffleupagus/move-errorWrapper-during-load

Prevent the loadingBar from overlaying the errorWrapper
Merge pull request #3576 from Snuffleupagus/undefined-stream-length

Enable loading of PDFs with undefined or missing stream lengths
Merge pull request #3583 from yurydelendik/workerSrc

Specifies default workerSrc
Fixes typo in 2-component image decoding
Merge pull request #3592 from yurydelendik/jpgjs-2comp

Fixes typo in 2-component image decoding
Merge pull request #3532 from yurydelendik/telem-1

Adds initial telemetry probes
Merge pull request #3573 from Rob--W/crx-view-local-files

[CRX] Fixes to view local files again