Fix is_opaque calculations in winscope

Test: open trace in bug and confirm app is visible behind screenshot
Fixes: 153694172
Change-Id: I60141afc3a28a5e51177d37fd20155c06dcf5882

tools/winscope/src/sf_visibility.js

@@ -77,7 +77,8 @@ function is_transform_invalid(transform) {
 }
 
 function is_opaque(layer) {
-  return layer.color == undefined || (layer.color.a || 0) < 1 || layer.isOpaque;
+  if (layer.color == undefined || layer.color.a == undefined || layer.color.a != 1) return false;
+  return layer.isOpaque;
 }
 
 function fills_color(layer) {