Don't draw the same triangles several times.
Bug #3388197

Change-Id: Ief1dfd9447f144e9992340a173d2893e5e049129
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 81c3407..2960395 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -1613,10 +1613,12 @@
             setupDrawColorFilter();
             setupDrawBlending(layer->blend || layer->alpha < 255, layer->mode, false);
             setupDrawProgram();
-            setupDrawDirtyRegionsDisabled();
             setupDrawPureColorUniforms();
             setupDrawColorFilterUniforms();
             setupDrawTexture(layer->texture);
+            // TODO: The current layer, if any, will be dirtied with the bounding box
+            //       of the layer we are drawing. Since the layer we are drawing has
+            //       a mesh, we know the dirty region, we should use it instead
             setupDrawModelViewTranslate(rect.left, rect.top, rect.right, rect.bottom);
             setupDrawMesh(&layer->mesh[0].position[0], &layer->mesh[0].texture[0]);