Modifying TextBlobCacheTest to use SkRandomScalerContext

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/adcdca86ce425cf8c28bfad311cef028df756ee8

Review URL: https://codereview.chromium.org/1266003002
diff --git a/src/gpu/GrAtlasTextContext.cpp b/src/gpu/GrAtlasTextContext.cpp
index 08fbf58..f597639 100644
--- a/src/gpu/GrAtlasTextContext.cpp
+++ b/src/gpu/GrAtlasTextContext.cpp
@@ -1678,8 +1678,10 @@
                         }
                         glyph = blob->fGlyphs[glyphOffset];
                         SkASSERT(glyph);
-                        SkASSERT(id == glyph->fPackedID &&
-                                 glyph->fMaskFormat == this->maskFormat());
+                        SkASSERT(id == glyph->fPackedID);
+                        // We want to be able to assert this but cannot for testing purposes.
+                        // once skbug:4143 has landed we can revist this assert
+                        //SkASSERT(glyph->fMaskFormat == this->maskFormat());
 
                         if (!fFontCache->hasGlyph(glyph) &&
                             !strike->addGlyphToAtlas(batchTarget, glyph, scaler, skGlyph,