Remove some attributes of Layout.

Runtime/ui/txt/layout.cs

 
 namespace Unity.UIWidgets.ui {
     class Layout {
-        int _start;
-        TabStops _tabStops;
 
         static float _x, _y, _maxX, _maxY; // Used to pass bounds from static to non-static doLayout
 
         }
 
-        public void doLayout(float offset, TextBuff buff, int start, int count, TextStyle style) {
-            this._start = start;
+        public void doLayout(float offset, TextBuff buff, int start, int count, TextStyle style, TabStops tabStops) {
-                this._tabStops);
+                tabStops);
             this._bounds.Set(_x, _y, _maxX - _x, _maxY - _y);
         }
 
         public static void requireEllipsisInTexture(string text, TextStyle style) {
             Font font = FontManager.instance.getOrCreate(style.fontFamily, style.fontWeight, style.fontStyle).font;
             font.RequestCharactersInTextureSafe(text, style.UnityFontSize, style.UnityFontStyle);
-        }
-
-        public void setTabStops(TabStops tabStops) {
-            this._tabStops = tabStops;
         }
 
         public void allocAdvancesAndPositions(int count) {

Runtime/ui/txt/paragraph.cs

             float maxWordWidth = 0;
 
             Layout layout = new Layout();
-            layout.setTabStops(this._tabStops);
             TextBlobBuilder builder = new TextBlobBuilder();
             GlyphPosition[] glyphPositions = new GlyphPosition[this._text.Length + (this._paragraphStyle.ellipsis?.Length ?? 0)];
             int pGlyphPositions = 0;
                 }
             }
 
-            layout.doLayout(runXOffset, new TextBuff(text), textStart, textCount, run.style);
+            layout.doLayout(runXOffset, new TextBuff(text), textStart, textCount, run.style, this._tabStops);
 
             builder.allocRunPos(run.style, text, textStart, textCount);
             // bounds relative to first character