Fix resizes back to initial remote session size

Since the expected client size wasn't updated when the browser window
resized, noVNC didn't resize the canvas properly when going back to
the exact same dimensions.

Fixes issue #1903

core/rfb.js

@@ -730,6 +730,7 @@ export default class RFB extends EventTargetMixin {
         window.requestAnimationFrame(() => {
             this._updateClip();
             this._updateScale();
+            this._saveExpectedClientSize();
         });
 
         if (this._resizeSession) {