Add deprecated MIME type to allowlist

b/245756622

The supported MIME type for javascript is text/javascript,
however on evergreen builds the six.moves SimpleHTTPServer
appears to use the deprecated application/javascript. As
a temporary workaround the allowlist in http_cache_transaction
will include this MIME type.

Change-Id: If8b893e588d068d444a6adb9e2b8bae4f930a142
(cherry picked from commit a6d43eee5091ad4dd97c316fbb7fc456f5b33817)
NOKEYCHECK=True
GitOrigin-RevId: 7b5ea71419f828da03956b91278f36c7083064e5

cobalt/black_box_tests/black_box_tests.py

@@ -63,8 +63,6 @@
     'allow_eval',
     'compression_test',
     'disable_eval_with_csp',
-    # http_cache is disabled due to flakiness. Planned update to make use of
-    # transferSize rather than load timings to make it more consistent.
     'http_cache',
     'persistent_cookie',
     'soft_mic_platform_service_test',

net/http/http_cache_transaction.cc

@@ -69,7 +69,7 @@ static const char* const kMimeTypesCacheAllowlist[] = {
     "text/html", "text/css",      "image/gif",  "image/jpeg",
     "image/png", "image/svg+xml", "image/webp", "font/otf",
     "font/ttf",  "font/woff",     "font/woff2", "text/javascript",
-    "example/unit_test"};
+    "example/unit_test", "application/javascript"};
 #endif
 
 constexpr TimeDelta kStaleRevalidateTimeout = TimeDelta::FromSeconds(60);