don't rely on fonts having a stream

src/fonts/SkTestScalerContext.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTestScalerContext_DEFINED
 #define SkTestScalerContext_DEFINED
 
@@ skipping 56 matching lines @@
     void getPath(const SkGlyph& glyph, SkPath* path);
 protected:
     SkScalerContext* onCreateScalerContext(const SkDescriptor* desc) const override;
     void onFilterRec(SkScalerContextRec* rec) const override;
     SkAdvancedTypefaceMetrics* onGetAdvancedTypefaceMetrics(
         PerGlyphInfo,
         const uint32_t* glyphIDs,
         uint32_t glyphIDsCount) const override;
 
     SkStreamAsset* onOpenStream(int* ttcIndex) const override {
-        SkASSERT(0);  // don't expect to get here
         return NULL;
     }
 
     void onGetFontDescriptor(SkFontDescriptor* desc, bool* isLocal) const override;
 
     int onCharsToGlyphs(const void* chars, Encoding encoding,
                         uint16_t glyphs[], int glyphCount) const override;
 
     int onCountGlyphs() const override {
         return (int) fTestFont->fCharCodesCount;
@@ skipping 16 matching lines @@
         return 0;
     }
 private:
     SkTestFont* fTestFont;
     friend class SkTestScalerContext;
 };
 
 SkTypeface* CreateTestTypeface(const char* name, SkTypeface::Style style);
 
 #endif