hterm: size notification: use × instead of x

We can handle Unicode just fine, so use × to display the dimensions.
This feels more proper than an ASCII x, and aligns with at least what
Wikipedia says:
https://en.wikipedia.org/wiki/Multiplication_sign#Uses
> Geometric dimension of an object, such as noting that a room is
> 10 feet × 12 feet in area.

Change-Id: Ia4a47fbcd94efb6a1b8ee0c9a5ff4a853659dd92
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/2563929
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/hterm/js/hterm_terminal.js b/hterm/js/hterm_terminal.js
index 1b18694..a7c07ef 100644
--- a/hterm/js/hterm_terminal.js
+++ b/hterm/js/hterm_terminal.js
@@ -3737,7 +3737,7 @@
  */
 hterm.Terminal.prototype.overlaySize = function() {
   if (this.prefs_.get('enable-resize-status')) {
-    this.showOverlay(`${this.screenSize.width} x ${this.screenSize.height}`);
+    this.showOverlay(`${this.screenSize.width} × ${this.screenSize.height}`);
   }
 };