fixes caching of inline images during parsing.

As described in #5444, the evaluator will perform identity checking of
paintImageMaskXObjects to decide if it can use
paintImageMaskXObjectRepeat instead of paintImageMaskXObjectGroup.

This can only ever work if the entry is a cache hit. However the
previous caching implementation was doing a lazy caching, which would
only consider a image cache worthy if it is repeated.
Only then the repeated instance would be cached.
As a result of this the sequence of identical images A1 A2 A3 A4 would
be seen as A1 A2 A2 A2 by the evaluator, which prevents using the
"repeat" optimization. Also only the last encountered image is cached,
so A1 B1 A2 B2, would stay A1 B1 A2 B2.

The new implementation drops the "lazy" init of the cache. The threshold
for enabling an image to be cached is rather small, so the potential waste
in storage and adler32 calculation is rather low. It also caches any
eligible image by its adler32.

The two example from above would now be A1 A1 A1 A1 and A1 B1 A1 B1
which not only saves temporary storage, but also prevents computing
identical masks over and over again (which is the main performance impact
of #2618)
Fix code style in extensions/firefox/content/PdfJs.jsm
Fix code style in extensions/firefox/content/PdfjsChromeUtils.jsm
Fix code style in extensions/firefox/content/PdfjsContentUtils.jsm
Fix code style in extensions/firefox/content/PdfJs-stub.jsm
Fix code style in extensions/firefox/content/PdfJsTelemetry.jsm
Fix code style in extensions/firefox/content/PdfJsTelemetry-addon.jsm
Fix code style in extensions/firefox/content/PdfStreamConverter.jsm
Update |node make lint| to also cover the Firefox specific *.jsm files
Refactor searching for the SOI marker of inline JPEG image streams
Improve fingerprinting of documents

Fixes two issues:
- #4456 : The first 100 bytes are often not unique as they can be
filled with standard PDF headers - so we use the first 200 KB instead.
(This may be overkill)
- Some documents we encountered have invalid xref ids, which were
always coming out as ‘0000000000000000’ - so we detect that and use the
MD5 instead.
Merge pull request #5508 from Snuffleupagus/jpeg-stream-find-soi

Refactor searching for the SOI marker of inline JPEG image streams
Merge pull request #5445 from CodingFabian/fixImageCachingInParser

Fixes caching of inline images during parsing.
Merge pull request #5124 from jordan-thoms/improve-fingerprinting

Improve fingerprinting of documents
Merge pull request #5406 from Snuffleupagus/lint-firefox-jsm

[Firefox] Enable linting of *.jsm files and update the code style in extensions/firefox/content