Use String.prototype.replaceAll() where appropriate

This fairly new method allows replacing *multiple* occurrences within a string without having to use regular expressions.

Please refer to:
 - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replaceAll
 - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replaceAll#browser_compatibility

src/core/catalog.js

@@ -989,7 +989,7 @@ class Catalog {
       if (javaScript === null) {
         javaScript = new Map();
       }
-      js = stringToPDFString(js).replace(/\u0000/g, "");
+      js = stringToPDFString(js).replaceAll("\x00", "");
       javaScript.set(name, js);
     }
 

src/core/core_utils.js

@@ -341,7 +341,7 @@ function _collectJS(entry, xref, list, parents) {
       } else if (typeof js === "string") {
         code = js;
       }
-      code = code && stringToPDFString(code).replace(/\u0000/g, "");
+      code = code && stringToPDFString(code).replaceAll("\x00", "");
       if (code) {
         list.push(code);
       }

src/core/file_spec.js

@@ -68,9 +68,9 @@ class FileSpec {
     if (!this._filename && this.root) {
       const filename = pickPlatformItem(this.root) || "unnamed";
       this._filename = stringToPDFString(filename)
-        .replace(/\\\\/g, "\\")
-        .replace(/\\\//g, "/")
-        .replace(/\\/g, "/");
+        .replaceAll("\\\\", "\\")
+        .replaceAll("\\/", "/")
+        .replaceAll("\\", "/");
     }
     return this._filename;
   }

src/display/content_disposition.js

@@ -199,7 +199,7 @@ function getFilenameFromContentDispositionHeader(contentDisposition) {
       function (matches, charset, encoding, text) {
         if (encoding === "q" || encoding === "Q") {
           // RFC 2047 section 4.2.
-          text = text.replace(/_/g, " ");
+          text = text.replaceAll("_", " ");
           text = text.replace(/=([0-9a-fA-F]{2})/g, function (match, hex) {
             return String.fromCharCode(parseInt(hex, 16));
           });