[WebSocket] Add tests for permessage deflate split frames.

Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py

Index: Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py
diff --git a/Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py b/Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py
index 109d04923656fa694d672cd21e4914c0eff70443..d224ae3942d7fe2cf77b988495ef6e28a1bf48dc 100644
--- a/Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py
+++ b/Tools/Scripts/webkitpy/thirdparty/mod_pywebsocket/util.py
@@ -331,8 +331,8 @@ class _RFC1979Deflater(object):
         self._window_bits = window_bits
         self._no_context_takeover = no_context_takeover
 
-    def filter(self, bytes, flush=True, bfinal=False):
-        if self._deflater is None or (self._no_context_takeover and flush):
+    def filter(self, bytes, end=True, bfinal=False):
+        if self._deflater is None:
             self._deflater = _Deflater(self._window_bits)
 
         if bfinal:
@@ -341,11 +341,17 @@ class _RFC1979Deflater(object):
             result = result + chr(0)
             self._deflater = None
             return result
-        if flush:
+
+        result = self._deflater.compress_and_flush(bytes)
+        if end:
             # Strip last 4 octets which is LEN and NLEN field of a
             # non-compressed block added for Z_SYNC_FLUSH.
-            return self._deflater.compress_and_flush(bytes)[:-4]
-        return self._deflater.compress(bytes)
+            result = result[:-4]
+
+        if self._no_context_takeover and end:
+            self._deflater = None
+
+        return result
 
 
 class _RFC1979Inflater(object):