Add ToUnicodeMap class.
Add IdentityToUnicodeMap class.

When loading the PDF from issue #4935, this change reduces peak RSS from
~2400 to ~300 MiB, and improves overall speed by ~81%, from 6336 ms to
1222 ms.
Simplify isIdentityUnicode detection.
Adds image and mask features, fixes clippath
Reduces amount of used memory during PNG creation.
Merge pull request #5162 from yurydelendik/pramodhkp-fixupgstate2

[SVG] Reduces amount of used memory during PNG creation.
only convert in IE9 if the requested responseType is actually an arraybuffer, otherwise just return the responseText. That way the compatibility.js does not break other frameworks like angular that not always want an array from xhr requests.
Nit fixes for svg.js
Merge pull request #5164 from timvandermeij/svg-nits

Nit fixes for svg.js
Merge branch 'master' of https://github.com/mozilla/pdf.js
Remove old unused code from PDFView.close()
Merge pull request #5150 from nnethercote/toUnicode

Fix #4935
Merge pull request #5160 from tomdw/feature/fix-angular-compatibility-ie9-conflict

only convert in IE9 if the requested responseType is actually an arraybu...
Removes bytesToString/stringToArray conversions in the font.js
Removes stringToArray
Fixes searchRange calculation
Merge pull request #5163 from yurydelendik/fontrefact

Refactoring of OpenType/TrueType font construction
Merge pull request #5166 from Snuffleupagus/pdfViewClose-cleanup

Remove old unused code from PDFView.close()
Uses float number formatter to print numbers in SVG
Merge pull request #5170 from yurydelendik/svgformatnumbers

[SVG] Uses float number formatter to print numbers in SVG