Speculative nullptr dereference fix for HarfBuzz face creation

third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzFace.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 314 matching lines @@
 {
 #if OS(MACOSX)
     hb_face_t* face = hb_coretext_face_create(m_platformData->cgFont());
 #else
     hb_face_t* face = nullptr;
 
     DEFINE_STATIC_LOCAL(BooleanHistogram,
         zeroCopySuccessHistogram,
         ("Blink.Fonts.HarfBuzzFaceZeroCopyAccess"));
     SkTypeface* typeface = m_platformData->typeface();
+    CHECK(typeface);
     int ttcIndex = 0;
     SkStreamAsset* typefaceStream = typeface->openStream(&ttcIndex);
-    if (typefaceStream->getMemoryBase()) {
+    if (typefaceStream && typefaceStream->getMemoryBase()) {
         std::unique_ptr<hb_blob_t, void(*)(hb_blob_t*)> faceBlob(hb_blob_create(
             reinterpret_cast<const char*>(typefaceStream->getMemoryBase()),
             typefaceStream->getLength(),
             HB_MEMORY_MODE_READONLY,
             typefaceStream,
             deleteTypefaceStream),
             hb_blob_destroy);
         face = hb_face_create(faceBlob.get(), ttcIndex);
     }
 
@@ skipping 26 matching lines @@
     m_platformData->setupPaint(&m_harfBuzzFontData->m_paint);
     m_harfBuzzFontData->m_rangeSet = rangeSet;
     m_harfBuzzFontData->m_simpleFontData = FontCache::fontCache()->fontDataFromFontPlatformData(m_platformData).get();
     ASSERT(m_harfBuzzFontData->m_simpleFontData);
     int scale = SkiaScalarToHarfBuzzPosition(m_platformData->size());
     hb_font_set_scale(m_unscaledFont, scale, scale);
     return m_unscaledFont;
 }
 
 } // namespace blink