Don't blindly trust toUnicode when building toFontChar for non-standard fonts without a font file (issue 4934)
Refactor fake worker loading (issue 3862)
Renames concatenateToArray to appendToArray
Zero the height and width of the Cached canvases before deleting.

This reduces peak RSS by about 300 MiB on my Mac when scrolling slowly through
the first 30 pages of a scanned black and white document.
faster JPEG transform
Let Parser_makeFilter return NullStream when an invalid stream is encountered (issue 3417)
Merge pull request #4955 from timvandermeij/rename-concatenate

Renames concatenateToArray to appendToArray
Merge pull request #4959 from nnethercote/zero-cache-canvases

Zero the height and width of cached canvases before deleting them.
Merge pull request #4950 from fkaelberer/fasterJPEGtransform

Faster JPEG transform
Added getOperatorList to api.js
Merge pull request #4951 from pramodhkp/getoperatorlist

Added getOperatorList to api.js
Disables broken rAF on iOS
Merge pull request #4946 from Snuffleupagus/issue-3862

Refactor fake worker loading (issue 3862)
Increases page cache size when needed
Merge pull request #4962 from yurydelendik/issue-4943

Increases page cache size when needed
Merge pull request #4961 from yurydelendik/raf-ios

Disables broken rAF on iOS
Splits shared/annotation.js into core/ and display/
Add ChunkedStream.ensureByte().

This new function is much faster than ensureRange(pos, pos+1), which is a very
common case.

This speeds up the rendering of some test cases (including the Tracemonkey
paper) by 4--5%.
Merge pull request #4966 from nnethercote/faster-ensureRange-2

Add ChunkedStream.ensureByte().
Build up textChunk.str more efficiently.

PartialEvaluator.getTextContent() builds up textChunk strings 1 char at a time,
creating many 100s of 1000s of intermediate strings along the way. This patch
make it instead push chars to an array and then join them at the end, as we
have done in numerous other places.