Allow mount content used in Stories to be preallocated

Summary: I have identified some mount components that were not being allowed to be preallocated. for the Stories Viewer I'm enabling them in this diff.

Reviewed By: pentiumao

Differential Revision: D53040049

fbshipit-source-id: 2c990da4dd0544e46e4e70bedcaffdb36ecd5cfc

litho-core/src/main/java/com/facebook/litho/DrawableComponent.java

@@ -109,6 +109,11 @@ public boolean isEquivalentProps(@Nullable Component o, boolean shouldCompareCom
     return DrawableUtils.isEquivalentTo(mDrawable, drawableComponent.mDrawable);
   }
 
+  @Override
+  public boolean canPreallocate() {
+    return true;
+  }
+
   private int getDrawableWidth() {
     return mDrawableWidth;
   }