fix(VP8): Scalability for FF 136+

For FF 136+ where DD extension is supported,  removing DD extension from the SDP will lead to broken scalabilty (the temporal scalability information will be missing and also DD extension header wont be included).

modules/RTC/TPCUtils.js

@@ -942,7 +942,10 @@ export class TPCUtils {
 
             if (isSender && mLine.ext?.length) {
                 const headerIndex = mLine.ext.findIndex(ext => ext.uri === DD_HEADER_EXT_URI);
-                const shouldNegotiateHeaderExts = codec === CodecMimeType.AV1 || codec === CodecMimeType.H264;
+                const shouldNegotiateHeaderExts = codec === CodecMimeType.AV1 || codec === CodecMimeType.H264
+
+                    // Removing DD ext header lines from the sdp breaks the scalability for FF with version 136+.
+                    || (codec === CodecMimeType.VP8 && browser.isFirefox());
 
                 if (!this.supportsDDHeaderExt && headerIndex >= 0) {
                     this.supportsDDHeaderExt = true;

modules/browser/BrowserCapabilities.js

@@ -233,8 +233,7 @@ export default class BrowserCapabilities extends BrowserDetection {
      * @returns {boolean}
      */
     supportsScalabilityModeAPI() {
-        return (this.isChromiumBased() && this.isEngineVersionGreaterThan(112))
-            || (this.isFirefox() && this.isVersionGreaterThan(135));
+        return this.isChromiumBased() && this.isEngineVersionGreaterThan(112);
     }
 
     /**