Test that headers are allowed to contain '.'s.

This and many other characters are surprisingly allowed by the relevant RFCs. But it turns out we implemented the RFCs correctly, so yay.

c++/src/kj/compat/http-test.c++

@@ -126,6 +126,7 @@ KJ_TEST("HttpHeaders::parseRequest") {
       "Content-Length: 123\r\n"
       "DATE:     early\r\n"
       "other-Header: yep\r\n"
+      "with.dots: sure\r\n"
       "\r\n");
   auto result = headers.tryParseRequest(text.asArray()).get<HttpHeaders::Request>();
 
@@ -143,12 +144,13 @@ KJ_TEST("HttpHeaders::parseRequest") {
   headers.forEach([&](kj::StringPtr name, kj::StringPtr value) {
     KJ_EXPECT(unpackedHeaders.insert(std::make_pair(name, value)).second);
   });
-  KJ_EXPECT(unpackedHeaders.size() == 5);
+  KJ_EXPECT(unpackedHeaders.size() == 6);
   KJ_EXPECT(unpackedHeaders["Content-Length"] == "123");
   KJ_EXPECT(unpackedHeaders["Host"] == "example.com");
   KJ_EXPECT(unpackedHeaders["Date"] == "early");
   KJ_EXPECT(unpackedHeaders["Foo-Bar"] == "Baz");
   KJ_EXPECT(unpackedHeaders["other-Header"] == "yep");
+  KJ_EXPECT(unpackedHeaders["with.dots"] == "sure");
 
   KJ_EXPECT(headers.serializeRequest(result.method, result.url) ==
       "POST /some/path HTTP/1.1\r\n"
@@ -157,6 +159,7 @@ KJ_TEST("HttpHeaders::parseRequest") {
       "Date: early\r\n"
       "Foo-Bar: Baz\r\n"
       "other-Header: yep\r\n"
+      "with.dots: sure\r\n"
       "\r\n");
 }