Remove aliases for BufferUtils in DrmEngine.

That alias was confusing the closure compiler, and causing it to
produce invalid output when making release versions.

Closes #2438

Change-Id: Ic232ce4f29222543b13c2cc725ffefaedea29e3a

lib/media/drm_engine.js

@@ -507,15 +507,12 @@ shaka.media.DrmEngine = class {
    * @param {!Uint8Array} initData
    */
   newInitData(initDataType, initData) {
-    // Aliases:
-    const BufferUtils = shaka.util.BufferUtils;
-
     // Suppress duplicate init data.
     // Note that some init data are extremely large and can't portably be used
     // as keys in a dictionary.
     const metadatas = this.activeSessions_.values();
     for (const metadata of metadatas) {
-      if (BufferUtils.equal(initData, metadata.initData)) {
+      if (shaka.util.BufferUtils.equal(initData, metadata.initData)) {
         shaka.log.debug('Ignoring duplicate init data.');
         return;
       }
@@ -1779,9 +1776,6 @@ shaka.media.DrmEngine = class {
     };
 
     for (const drmInfo of drmInfos) {
-      // Aliases:
-      const BufferUtils = shaka.util.BufferUtils;
-
       // Build an array of unique license servers.
       if (!licenseServers.includes(drmInfo.licenseServerUri)) {
         licenseServers.push(drmInfo.licenseServerUri);
@@ -1790,7 +1784,8 @@ shaka.media.DrmEngine = class {
       // Build an array of unique server certs.
       if (drmInfo.serverCertificate) {
         const found = serverCerts.some(
-            (cert) => BufferUtils.equal(cert, drmInfo.serverCertificate));
+            (cert) => shaka.util.BufferUtils.equal(
+                cert, drmInfo.serverCertificate));
         if (!found) {
           serverCerts.push(drmInfo.serverCertificate);
         }