Implement redirect() API for Fetch Response

LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js

Index: LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js
diff --git a/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js b/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js
index e513806c87eeae29729c6f9208f215258a980d6d..a74b95673c53fee538ead69deffa0f73278e0b6e 100644
--- a/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js
+++ b/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js
@@ -182,6 +182,14 @@ var VALID_REASON_PHRASE = [
   '', '0123456789', '404 Not Found', 'HTTP/1.1 404 Not Found', 'AZ\u00ffaz',
   'x'.repeat(100000)];
 
+var INVALID_URLS =
+  ['http://',
+   'https://',
+   'http://ex%00ample.com',
+   'http://ex%0dample.com',
+   'http://ex%0aample.com',
+   'http://ex%08ample.com'];

[hiroshige, 2015/04/27 11:47:25]

Could you also add the following? (I'd like to test the invalid characters
directly embedded in the strings)
'http://ex\x00ample.com'
'http://ex\x0dample.com'
'http://ex\x0aample.com'

[shiva.jm, 2015/04/28 06:06:48]

when tried with 'http://ex\x0dample.com', it did not throw the error. But with
'http://ex\0xdample.com', it give error.

[hiroshige, 2015/04/28 10:48:23]

Hmm.
'http://ex\x00ample.com' throws TypeError.
'http://ex\x0dample.com' and 'http://ex\x0aample.com' don't throw exceptions,
because they are normalized to 'http://example.com' (by
DoRemoveURLWhitespace()?)
https://code.google.com/p/chromium/codesearch#chromium/src/url/url_canon_etc....

Could you add 'http://ex\x00ample.com' to INVALID_URLS, and tests for another
two in response.js, like:

test(function() {
    ['http://ex\x0aample.com',
     'http://ex\x0dample.com'].forEach(function(url) {
        assert_equals(Response.redirect(url).headers.get('Location'),
                      'http://example.com/',
                      'Location header value must not contain CR or LF');
      });
  }, 'Response.redirect() with URLs with CR or LF');

I'm not sure what to do for those URLs in the spec, but checking header values
do not contain CR/LF/null byte will be useful for us.

+
 function size(headers) {
   var count = 0;
   for (var header of headers) {