Indent the stepper on save/restore.

Makes it easier to debug and visualize the graphics
state changes in the debugger.

web/debugger.js

@@ -292,6 +292,7 @@ const Stepper = (function StepperClosure() {
       this.breakPoints = initialBreakPoints;
       this.currentIdx = -1;
       this.operatorListIdx = 0;
+      this.indentLevel = 0;
     }
 
     init(operatorList) {
@@ -382,8 +383,14 @@ const Stepper = (function StepperClosure() {
           table.appendChild(charCodeRow);
           table.appendChild(fontCharRow);
           table.appendChild(unicodeRow);
+        } else if (fn === "restore") {
+          this.indentLevel--;
         }
-        line.appendChild(c("td", fn));
+        line.appendChild(c("td", " ".repeat(this.indentLevel * 2) + fn));
+        if (fn === "save") {
+          this.indentLevel++;
+        }
+
         if (decArgs instanceof HTMLElement) {
           line.appendChild(decArgs);
         } else {

web/viewer.css

@@ -1701,6 +1701,7 @@ html[dir="rtl"] #documentPropertiesOverlay .row > * {
 }
 #PDFBug table {
   font-size: 10px;
+  white-space: pre;
 }
 #PDFBug table.showText {
   border-collapse: collapse;