Temporary SimpleFontData leaked in RemoteFontFaceSource

Fix leak in RemoteFontFaceSource where a temporary SimpleFontData
instance was not de-referenced and hence never destroyed.

The leak was introduced by the refactorings made in this commit:
https://chromium-review.googlesource.com/c/chromium/src/+/691475

Change-Id: I6473702a53e83f5fdfbe0fe84ede675c41c5ddad
Reviewed-on: https://chromium-review.googlesource.com/c/1286451Reviewed-by: Anders Ruud <andruud@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600654}

third_party/blink/renderer/core/css/remote_font_face_source.cc

@@ -235,9 +235,9 @@ RemoteFontFaceSource::CreateLoadingFallbackFontData(
     const FontDescription& font_description) {
   // This temporary font is not retained and should not be returned.
   FontCachePurgePreventer font_cache_purge_preventer;
-  SimpleFontData* temporary_font =
-      FontCache::GetFontCache()->GetNonRetainedLastResortFallbackFont(
-          font_description);
+  scoped_refptr<SimpleFontData> temporary_font =
+      FontCache::GetFontCache()->GetLastResortFallbackFont(font_description,
+                                                           kDoNotRetain);
   if (!temporary_font) {
     NOTREACHED();
     return nullptr;