trivial fix for TextBlobCache

src/gpu/GrTextBlobCache.h

Index: src/gpu/GrTextBlobCache.h
diff --git a/src/gpu/GrTextBlobCache.h b/src/gpu/GrTextBlobCache.h
index 9ce4ec7af2553c0b291eee588aad44be91f9ffe9..1b5e5b8803865c8f92e6c1d11bca6a670f62572c 100644
--- a/src/gpu/GrTextBlobCache.h
+++ b/src/gpu/GrTextBlobCache.h
@@ -65,8 +65,10 @@ public:
             SkASSERT(lruBlob);
             while (fPool.size() > kBudget && (lruBlob = iter.get()) && lruBlob != blob) {
                 fCache.remove(lruBlob->fUniqueID);
-                fBlobList.remove(lruBlob);
+
+                // Backup the iterator before removing and unrefing the blob
                 iter.prev();
+                fBlobList.remove(lruBlob);
                 lruBlob->unref();
             }