GUAC-958: Simplify resize handling (use directive). Only install resize handler after object loads.

guacamole/src/main/webapp/app/osk/styles/osk.css

@@ -24,18 +24,6 @@
     position: relative;
 }
 
-.osk .resize-sensor {
-    height: 100%;
-    width: 100%;
-    position: absolute;
-    left: 0;
-    top: 0;
-    overflow: hidden;
-    border: none;
-    opacity: 0;
-    z-index: -1;
-}
-
 .guac-keyboard {
     display: inline-block;
     width: 100%;