Find a maximum dimension give a list of SkGlyphIDs

In order to simplify buffer and strike handling eventually,
add a routine that will allow finding the maximum dimension of a
list of glyphs. In a future CL, I will use this to simplify
handling calculating the scale factor needed in the drawing of
last resort.

Change-Id: I8ac47328e1dfe59ea80499a83253bb166172a6b0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/552684
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
5 files changed