Apply bilinear filtering on text only when necessary.

Change-Id: Ic903f4b5d30e9c92528c6291941896efe4729ee3
diff --git a/libs/hwui/Matrix.h b/libs/hwui/Matrix.h
index 0608efe..fe81159 100644
--- a/libs/hwui/Matrix.h
+++ b/libs/hwui/Matrix.h
@@ -103,6 +103,8 @@
         multiply(u);
     }
 
+    bool changesBounds();
+
     void copyTo(float* v) const;
     void copyTo(SkMatrix& v) const;