Fix bug with accelerated translucent rendering

There was a bug in the dirty region optimizations when
using alpha layers. This prevented translucent objects from
being drawn at all in many situations.

Change-Id: I23e9bce3595fbd6fe2bda15e8753a0f35baffb82

libs/hwui/OpenGLRenderer.cpp

@@ -647,6 +647,9 @@ void OpenGLRenderer::composeLayerRect(Layer* layer, const Rect& rect, bool swap)
 void OpenGLRenderer::composeLayerRegion(Layer* layer, const Rect& rect) {
 #if RENDER_LAYERS_AS_REGIONS
     if (layer->region.isRect()) {
+        const android::Rect& bounds = layer->region.getBounds();
+        layer->regionRect.set(bounds.leftTop().x, bounds.leftTop().y,
+                bounds.rightBottom().x, bounds.rightBottom().y);
         composeLayerRect(layer, layer->regionRect);
         layer->region.clear();
         return;