Stop using deprecated/SkPaint-based SkTextBlobBuilder APIs

Convert the only client relying on the old API to the SkFont version.

TBR=

Bug: skia:2664
Change-Id: Ic4420a9e5d43dfc0edf6e4c23229be94e48c3e13
Reviewed-on: https://chromium-review.googlesource.com/c/1347309
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
Cr-Commit-Position: refs/heads/master@{#610429}

ui/gfx/render_text.cc

@@ -231,7 +231,7 @@ void SkiaTextRenderer::DrawPosText(const SkPoint* pos,
                                    const uint16_t* glyphs,
                                    size_t glyph_count) {
   SkTextBlobBuilder builder;
-  const auto& run_buffer = builder.allocRunPos(flags_.ToSkPaint(), glyph_count);
+  const auto& run_buffer = builder.allocRunPos(flags_.ToSkFont(), glyph_count);
 
   static_assert(sizeof(*glyphs) == sizeof(*run_buffer.glyphs), "");
   memcpy(run_buffer.glyphs, glyphs, glyph_count * sizeof(*glyphs));