Normalize and update the header value checks to RFC 7230 for Fetch

LayoutTests/http/tests/fetch/script-tests/headers.js

 if (self.importScripts) {
   importScripts('../resources/fetch-test-helpers.js');
 }
 
 test(function() {
     var expectedValueMap = {
       'content-language': 'ja',
       'content-type': 'text/html; charset=UTF-8',
       'x-fetch-test': 'response test field'
     };
@@ skipping 158 matching lines @@
     headers.set('a', 'x');
     assert_equals(headers.get('a'), 'x');
     assert_equals(headers2.get('a'), 'b');
 
     // new Headers with Dictionary
     headers = new Headers({'a': 'b', 'c': 'd'});
     assert_equals(size(headers), 2, 'headers size should match');
     assert_equals(headers.get('a'), 'b');
     assert_equals(headers.get('c'), 'd');
 
+    // new valid Headers values
+    headers = new Headers();
+    headers.set('a', '\xd0\xa1');
+    assert_equals(headers.get('a'), '\xd0\xa1');
+    headers.append('b', 't t');
+    assert_equals(headers.get('b'), 't t');
+    headers.append('c', 't\tt');
+    assert_equals(headers.get('c'), 't\tt');
+
+    // test for removing leading and trailing white spaces

[hiroshige, 2015/09/09 07:01:48]

nit: How about "Tests for normalizing header values."?
- s/test/Tests/
- Add a period at the end of the statement.
- Including the word of "normalize" or so will help readers to correspond the
tests with the spec.

[shiva.jm, 2015/09/10 10:10:26]

Done.

+    headers.append('d', ' t');
+    assert_equals(headers.get('d'), 't');
+    headers.set('e', 't ');
+    assert_equals(headers.get('d'), 't');
+    headers.append('f', ' t ');
+    assert_equals(headers.get('f'), 't');
+    headers.append('g', 'test\r');
+    assert_equals(headers.get('g'), 'test');
+    headers.set('h', 'test\n');
+    assert_equals(headers.get('h'), 'test');
+    headers.append('i', 'test\r\n');
+    assert_equals(headers.get('i'), 'test');
+    headers.append('j', 'test\t');
+    assert_equals(headers.get('j'), 'test');
+
     // Throw errors
     INVALID_HEADER_NAMES.forEach(function(name) {
         assert_throws({name: 'TypeError'},
                       function() {
                         var obj = {};
                         obj[name] = 'a';
                         var headers = new Headers(obj);
                       },
                       'new Headers with an invalid name (' + name +
                       ') should throw');
@@ skipping 26 matching lines @@
                   'new Headers with a sequence with less than two strings ' +
                   'should throw');
     assert_throws({name: 'TypeError'},
                   function() { var headers = new Headers([['a', 'b'],
                                                           ['x', 'y', 'z']]); },
                   'new Headers with a sequence with more than two strings ' +
                   'should throw');
   }, 'Headers');
 
 done();