don't draw strings that have no glyphs

This string had several characters which resulted in zero
glyphs. Having zero glyphs bypassed the buffer sizing code,
and continued to process the glyph run list assuming it had
7 runs because the buffer sizing code also clears the run list.
This caused the code to process runs from a previous SkTextBlob,
which was already deleted.

If the there are no glyphs, call the buffer sizing code to
set up all the invariants. Exit if there are no runs produced.

Bug: oss-fuzz:33915

Change-Id: I9f3f38a58112c44ddd65265c68d982b3b0dcd79c
Reviewed-by: Ben Wagner <>
Commit-Queue: Herb Derby <>
3 files changed