bpo:41989 Fix htmlparser "unclosed script tag causes data loss"

When calling .close() the htmlparser should flush all remaining content,
even when that content is in an unclosed script or style tag.

Lib/html/parser.py

@@ -241,7 +241,7 @@ class HTMLParser(_markupbase.ParserBase):
             else:
                 assert 0, "interesting.search() lied"
         # end while
-        if end and i < n and not self.cdata_elem:
+        if end and i < n:
             if self.convert_charrefs and not self.cdata_elem:
                 self.handle_data(unescape(rawdata[i:n]))
             else:

Lib/test/test_htmlparser.py

@@ -315,6 +315,16 @@ text
                                 ("endtag", element_lower)],
                             collector=Collector(convert_charrefs=False))
 
+    def test_EOF_in_cdata(self):
+        content = """<!-- not a comment --> &not-an-entity-ref;
+                  <a href="" /> </p><p> <span></span></style>
+                  '</script' + '>'"""
+        s = f'<script>{content}'
+        self._run_check(s, [
+            ("starttag", 'script', []),
+            ("data", content)
+        ])
+
     def test_comments(self):
         html = ("<!-- I'm a valid comment -->"
                 '<!--me too!-->'