Bug 1710081 [wpt PR 28896] - Drop read_gzp workaround for a mypy problem in Python 2, a=testonly

Automatic update from web-platform-tests
Drop read_gzp workaround for a mypy problem in Python 2 (#28896)

There's no issue here with mypy on Python 3.

Part of https://github.com/web-platform-tests/wpt/pull/28895.
--

wpt-commits: e953dffdcee1a2a276ea0b73c15e3c6e04d4683f
wpt-pr: 28896

testing/web-platform/tests/tools/manifest/download.py

@@ -158,7 +158,7 @@ def download_manifest(
             fileobj = io.BytesIO(resp.read())
             try:
                 with gzip.GzipFile(fileobj=fileobj) as gzf:
-                    data = read_gzf(gzf)  # type: ignore
+                    data = gzf.read()
                     decompressed = data
             except IOError:
                 logger.warning("Failed to decompress downloaded file")
@@ -180,12 +180,6 @@ def download_manifest(
     return True
 
 
-def read_gzf(gzf):  # type: ignore
-    # This is working around a mypy problem in Python 2:
-    # "Call to untyped function "read" in typed context"
-    return gzf.read()
-
-
 def create_parser():
     # type: () -> argparse.ArgumentParser
     parser = argparse.ArgumentParser()