fix(UI): Fix erroneous current time when dragging (#8558)

Fixes #8557

Author: avelad

ui/seek_bar.js

@@ -198,11 +198,11 @@ shaka.ui.SeekBar = class extends shaka.ui.RangeElement {
       const min = parseFloat(this.bar.min);
       const max = parseFloat(this.bar.max);
       // Pixels from the left of the range element
-      const mousePosition = event.clientX - rect.left;
+      const mousePosition = Math.max(0, event.clientX - rect.left);
       // Pixels per unit value of the range element.
       const scale = (max - min) / rect.width;
       // Mouse position in units, which may be outside the allowed range.
-      const value = Math.round(min + scale * mousePosition);
+      const value = Math.min(max, Math.round(min + scale * mousePosition));
       if (!this.player.getImageTracks().length) {
         this.hideThumbnail_();
         this.showTime_(mousePosition, value);