adding assert to GrAtlasTextContext

TBR=bsalomon@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/1241263003
diff --git a/src/gpu/GrAtlasTextBlob.cpp b/src/gpu/GrAtlasTextBlob.cpp
index d357145..3fb7ac9 100644
--- a/src/gpu/GrAtlasTextBlob.cpp
+++ b/src/gpu/GrAtlasTextBlob.cpp
@@ -57,7 +57,7 @@
             SkASSERT(!rRun.fTypeface.get());
         }
 
-        // TODO BOUNDS ARE ALL MESSED UP
+        // We offset bounds right before flush time so they will not be correct here
         //SkASSERT(lRun.fVertexBounds == rRun.fVertexBounds);
 
         SkASSERT(lRun.fDescriptor.getDesc());