wire up reduced atlas and zero textblob cache to test

src/gpu/GrTextBlobCache.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextBlobCache_DEFINED
 #define GrTextBlobCache_DEFINED
 
@@ skipping 99 matching lines @@
     }
 
 private:
     typedef SkTInternalLList<GrAtlasTextBlob> BitmapBlobList;
 
     void checkPurge(GrAtlasTextBlob* blob = NULL) {
         // If we are overbudget, then unref until we are below budget again
         if (fPool.size() > fBudget) {
             BitmapBlobList::Iter iter;
             iter.init(fBlobList, BitmapBlobList::Iter::kTail_IterStart);
-            GrAtlasTextBlob* lruBlob = iter.get();
-            SkASSERT(lruBlob);
+            GrAtlasTextBlob* lruBlob = NULL;
             while (fPool.size() > fBudget && (lruBlob = iter.get()) && lruBlob != blob) {
                 fCache.remove(lruBlob->fKey);
 
                 // Backup the iterator before removing and unrefing the blob
                 iter.prev();
                 fBlobList.remove(lruBlob);
                 lruBlob->unref();
             }
 
             // If we break out of the loop with lruBlob == blob, then we haven't purged enough
@@ skipping 18 matching lines @@
     static const int kDefaultBudget = 1 << 22;
     BitmapBlobList fBlobList;
     SkTDynamicHash<GrAtlasTextBlob, GrAtlasTextBlob::Key> fCache;
     GrMemoryPool fPool;
     PFOverBudgetCB fCallback;
     void* fData;
     size_t fBudget;
 };
 
 #endif