fix: Install polyfills for Comcast X1 devices

lib/polyfill/media_capabilities.js

@@ -61,7 +61,8 @@ shaka.polyfill.MediaCapabilities = class {
         shaka.util.Platform.isWebOS() ||
         shaka.util.Platform.isTizen() ||
         shaka.util.Platform.isEOS() ||
-        shaka.util.Platform.isHisense()) {
+        shaka.util.Platform.isHisense() ||
+        shaka.util.Platform.isComcastX1()) {
       canUseNativeMCap = false;
     }
     if (canUseNativeMCap && navigator.mediaCapabilities) {

lib/polyfill/mediasource.js

@@ -87,6 +87,18 @@ shaka.polyfill.MediaSource = class {
       // the player from trying to play opus on Tizen, we will override media
       // source to always reject opus content.
       shaka.polyfill.MediaSource.rejectCodec_('opus');
+    } else if (shaka.util.Platform.isComcastX1()) {
+      // XOne look to be like safari 8 which do not correctly
+      // implement abort() on SourceBuffer.
+      // Calling abort() before appending a segment causes that segment to be
+      // incomplete in the buffer.
+      // Bug filed: https://bugs.webkit.org/show_bug.cgi?id=165342
+      shaka.polyfill.MediaSource.stubAbort_();
+      // If you remove up to a keyframe, Webkit 601.x.x incorrectly will also
+      // remove that keyframe and the content up to the next.
+      // Offsetting the end of the removal range seems to help.
+      // Bug filed: https://bugs.webkit.org/show_bug.cgi?id=177884
+      shaka.polyfill.MediaSource.patchRemovalRange_();
     } else {
       shaka.log.info('Using native MSE as-is.');
     }

lib/util/platform.js

@@ -300,7 +300,7 @@ shaka.util.Platform = class {
         !shaka.util.Platform.isOrange() &&
         !shaka.util.Platform.isPS4() &&
         !shaka.util.Platform.isAmazonFireTV() &&
-        !shaka.util.Platform.isWPE() &&
+        !shaka.util.Platform.isComcastX1() &&
         !shaka.util.Platform.isZenterio() &&
         !shaka.util.Platform.isSkyQ();
   }
@@ -368,7 +368,7 @@ shaka.util.Platform = class {
    * Check if the current platform is Comcast X1.
    * @return {boolean}
    */
-  static isWPE() {
+  static isComcastX1() {
     return shaka.util.Platform.userAgentContains_('WPE');
   }
 
@@ -536,7 +536,7 @@ shaka.util.Platform = class {
         Platform.isPS5() || Platform.isAmazonFireTV() ||
         Platform.isEOS() || Platform.isAPL() ||
         Platform.isVirginMedia() || Platform.isOrange() ||
-        Platform.isWPE() || Platform.isChromecast() ||
+        Platform.isComcastX1() || Platform.isChromecast() ||
         Platform.isHisense() || Platform.isZenterio()) {
       return true;
     }