diff --git a/telemetry/telemetry/core/memory_cache_http_server.py b/telemetry/telemetry/core/memory_cache_http_server.py
index <HASH>..<HASH> 100644
--- a/telemetry/telemetry/core/memory_cache_http_server.py
+++ b/telemetry/telemetry/core/memory_cache_http_server.py
@@ -70,7 +70,8 @@ class MemoryCacheHTTPServer(SocketServer.ThreadingMixIn,
           fs = os.fstat(fd.fileno())
           content_type = mimetypes.guess_type(file_path)[0]
           zipped = False
-          if content_type and content_type.startswith('text/'):
+          if content_type in ['text/html', 'text/css',
+                              'application/javascript']:
             zipped = True
             response = zlib.compress(response, 9)
           self.resource_map[file_path] = {
[Telemetry] Compress JavaScript in addition to HTML/CSS.

This saves about another 3MB of server memory usage on the intl1 page cycler.

BUG=<I>
TEST=intl1 page cycler on mac
NOTRY=True
TBR=<EMAIL>


Review URL: <URL>