fix buffers not clearing

src/browser/Terminal.ts

@@ -1308,6 +1308,7 @@ export class Terminal extends CoreTerminal implements ITerminal {
       // Don't clear if it's already clear
       return;
     }
+    this.buffer.clearMarkers();
     this.buffer.lines.set(0, this.buffer.lines.get(this.buffer.ybase + this.buffer.y)!);
     this.buffer.lines.length = 1;
     this.buffer.ydisp = 0;