Bring back node fallbacks, originally added in #5556.

I r+ed their removal in #5584 because node supports CompressionStream,
but I forgot to ask for the fallbacks to be put back when we switched
back to using a worker.

Author: mstange

src/utils/gz.ts

@@ -34,12 +34,45 @@ export async function compress(
   // Encode the data if it's a string
   const arrayData =
     typeof data === 'string' ? new TextEncoder().encode(data) : data;
+
+  if (!(typeof window === 'object' && 'Worker' in window)) {
+    // Try to fall back to Node's zlib library.
+    const zlib = await import('zlib');
+    return new Promise((resolve, reject) => {
+      zlib.gzip(data, (errorOrNull, result) => {
+        if (errorOrNull) {
+          reject(errorOrNull);
+        } else {
+          resolve(new Uint8Array(result.buffer as ArrayBuffer));
+        }
+      });
+    });
+  }
+
   return runGzWorker('compress', arrayData);
 }
 
 export async function decompress(
   data: Uint8Array<ArrayBuffer>
 ): Promise<Uint8Array<ArrayBuffer>> {
+  if (!(typeof window === 'object' && 'Worker' in window)) {
+    // Handle the case where we're not running in the browser, e.g. when
+    // this code is used as part of a library in a Node project.
+    // We don't get here when running Firefox profiler tests, because our
+    // tests create a mock window with a mock Worker class.
+    // Try to fall back to Node's zlib library.
+    const zlib = await import('zlib');
+    return new Promise((resolve, reject) => {
+      zlib.gunzip(data, (errorOrNull, result) => {
+        if (errorOrNull) {
+          reject(errorOrNull);
+        } else {
+          resolve(new Uint8Array(result.buffer as ArrayBuffer));
+        }
+      });
+    });
+  }
+
   return runGzWorker('decompress', data);
 }