Factor out overload-set handling from symbol lookup.

Symbol name lookup is generally simple, except for overload handling.
This factors out the complex, rarely-hit parts into a separate function.
Also, this replaces a vector with a span, which is probably a wash
since it's generally either empty or needs to be modified.

Change-Id: Ia4207fabc08e11b0214406de372cf429c4967ffd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/548158
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed