Cannot create SkFontData with no data.

Bug: oss-fuzz:26254
Change-Id: Ia4ce4eabacbd9811bc0fdf09b509fd69650cce53
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/327816
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

Author: Ben Wagner

src/core/SkFontDescriptor.cpp

@@ -56,7 +56,7 @@ static size_t SK_WARN_UNUSED_RESULT read_id(SkStream* stream) {
 }
 
 std::unique_ptr<SkFontData> SkFontDescriptor::maybeAsSkFontData() {
-    if (!fVariationDataIsOldAndBad) {
+    if (!fVariationDataIsOldAndBad || !this->hasStream()) {
         return nullptr;
     }
     SkFontArguments args;