code_generation_hashes json files end with newline

Bug: None
Change-Id: Iddd2c1777a1d5486a4d390c6e3d56ffb09f47f02
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4574569
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Auto-Submit: Roman Lavrov <romanl@google.com>
Commit-Queue: Roman Lavrov <romanl@google.com>

scripts/run_code_generation.py

@@ -270,12 +270,9 @@ def main():
 
         for fname, new_hashes in all_new_hashes.items():
             hash_fname = os.path.join(hash_dir, fname)
-            json.dump(
-                new_hashes,
-                open(hash_fname, "w"),
-                indent=2,
-                sort_keys=True,
-                separators=(',', ':\n    '))
+            with open(hash_fname, "w") as f:
+                json.dump(new_hashes, f, indent=2, sort_keys=True, separators=(',', ':\n    '))
+                f.write('\n')  # json.dump doesn't end with newline
 
 
 if __name__ == '__main__':