Support: Reduce size

Pros:
```
   raw     gz Sizes
282255  84119 dist/jquery.js
 95647  33205 dist/jquery.min.js

   raw     gz Compared to 1.x-master @ a96ff1c3a864cee27ac3014b63b7054bb938c30d
 -1824   -222 dist/jquery.js
  -883   -247 dist/jquery.min.js
```

Cons:
* Consolidated CSS support tests may incur a few ms extra delay on first run