Use string concatenation instead of array join for making RPC URLs (#2301)

Author: 0xHexE

packages/firestore/src/platform_browser/webchannel_connection.ts

@@ -415,16 +415,16 @@ export class WebChannelConnection implements Connection {
   makeUrl(rpcName: string): string {
     const urlRpcName = RPC_NAME_REST_MAPPING[rpcName];
     assert(urlRpcName !== undefined, 'Unknown REST mapping for: ' + rpcName);
-    const url = [this.baseUrl, '/', RPC_URL_VERSION];
-    url.push('/projects/');
-    url.push(this.databaseId.projectId);
-
-    url.push('/databases/');
-    url.push(this.databaseId.database);
-    url.push('/documents');
-
-    url.push(':');
-    url.push(urlRpcName);
-    return url.join('');
+    return (
+      this.baseUrl +
+      '/' +
+      RPC_URL_VERSION +
+      '/projects/' +
+      this.databaseId.projectId +
+      '/databases/' +
+      this.databaseId.database +
+      '/documents:' +
+      urlRpcName
+    );
   }
 }