Only use data-font-name attributes when necessary.

The data-font-name attribute of textLayer divs are only used by the Font
Inspector. This change ensures they are only present when the pdfBug
tools are enabled.
Remove setGStateForKey() closure.

setGStateForKey() is a closure that serves no particularly useful
purpose. This change inlines it at the single call site. This avoids 1.7
MiB of allocations (because closures are objects) for the MTA map
mentioned in https://bugzilla.mozilla.org/show_bug.cgi?id=835380#c17.
Merge pull request #5205 from nnethercote/setGState-closure

Remove setGStateForKey() closure.
Merge pull request #5193 from nnethercote/data-font-name

Only use data-font-name attributes when necessary.
Fixes Type3 negative font direction
Merge pull request #5210 from yurydelendik/type3dir

Fixes Type3 negative font direction