fix: Fix dropdowndiv animations (#9733)

packages/blockly/core/css.ts

@@ -123,7 +123,7 @@ const content = `
   left: 0;
   top: 0;
   z-index: 1000;
-  display: none;
+  visibility: hidden;
   border: 1px solid;
   border-color: #dadce0;
   background-color: #fff;

packages/blockly/core/dropdowndiv.ts

@@ -760,7 +760,7 @@ function positionInternal(
   div.style.top = initialY + 'px';
 
   // Show the div.
-  div.style.display = 'block';
+  div.style.visibility = 'visible';
   div.style.opacity = '1';
   // Add final translate, animated through `transition`.
   // Coordinates are relative to (initialX, initialY),