Revert "Remove the unused Font.prototype.spaceWidth getter (PR 13424 follow-up)"

This reverts commit 4aee67227e.

src/core/fonts.js

@@ -3293,6 +3293,44 @@ class Font {
     return builder.toArray();
   }
 
+  get spaceWidth() {
+    // trying to estimate space character width
+    const possibleSpaceReplacements = ["space", "minus", "one", "i", "I"];
+    let width;
+    for (const glyphName of possibleSpaceReplacements) {
+      // if possible, getting width by glyph name
+      if (glyphName in this.widths) {
+        width = this.widths[glyphName];
+        break;
+      }
+      const glyphsUnicodeMap = getGlyphsUnicode();
+      const glyphUnicode = glyphsUnicodeMap[glyphName];
+      // finding the charcode via unicodeToCID map
+      let charcode = 0;
+      if (this.composite && this.cMap.contains(glyphUnicode)) {
+        charcode = this.cMap.lookup(glyphUnicode);
+
+        if (typeof charcode === "string") {
+          charcode = convertCidString(glyphUnicode, charcode);
+        }
+      }
+      // ... via toUnicode map
+      if (!charcode && this.toUnicode) {
+        charcode = this.toUnicode.charCodeOf(glyphUnicode);
+      }
+      // setting it to unicode if negative or undefined
+      if (charcode <= 0) {
+        charcode = glyphUnicode;
+      }
+      // trying to get width via charcode
+      width = this.widths[charcode];
+      if (width) {
+        break; // the non-zero width found
+      }
+    }
+    return shadow(this, "spaceWidth", width || this.defaultWidth);
+  }
+
   /**
    * @private
    */