Fix - prevent code injection via plain text

TObjString painted via drawRawText function, which was using html for text.
This is potentially risky therefore use text() function
which does not parse inner text and does not create extra elements

Author: linev

modules/base/ObjectPainter.mjs

@@ -1642,24 +1642,24 @@ function drawRawText(dom, txt /* , opt */) {
       if (!isStr(stxt))
          stxt = '<undefined>';
 
-      const mathjax = this.txt.mathjax || (settings.Latex === constants.Latex.AlwaysMathJax);
-
-      if (!mathjax && !('as_is' in this.txt)) {
-         const arr = stxt.split('\n');
-         stxt = '';
-         for (let i = 0; i < arr.length; ++i)
-            stxt += `<pre style='margin:0'>${arr[i]}</pre>`;
-      }
-
-      const frame = this.selectDom();
+      const mathjax = this.txt.mathjax || (settings.Latex === constants.Latex.AlwaysMathJax),
+            frame = this.selectDom();
       let main = frame.select('div');
       if (main.empty())
          main = frame.append('div').attr('style', 'max-width:100%;max-height:100%;overflow:auto');
-      main.html(stxt);
+      else
+         main.html('');
 
       // (re) set painter to first child element, base painter not requires canvas
       this.setTopPainter();
 
+      if (!mathjax && !('as_is' in this.txt)) {
+         const arr = stxt.split('\n');
+         for (let i = 0; i < arr.length; ++i)
+            main.append('pre').style('margin', '0').text(arr[i]);
+      } else
+         main.text(stxt);
+
       if (mathjax)
          typesetMathjax(frame.node());