Auto merge of #12416 - canaltinova:referrer, r=jdm

Implement Document.referrer

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---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12389 (github issue number if applicable).

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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tests/wpt/metadata/XMLHttpRequest/responsexml-document-properties.htm.ini

@@ -3,9 +3,6 @@
   [domain]
     expected: FAIL
 
-  [referrer]
-    expected: FAIL
-
   [readyState]
     expected: FAIL
 

tests/wpt/metadata/html/dom/interfaces.html.ini

@@ -3,9 +3,6 @@
   [Document interface: attribute domain]
     expected: FAIL
 
-  [Document interface: attribute referrer]
-    expected: FAIL
-
   [Document interface: attribute dir]
     expected: FAIL
 
@@ -6987,9 +6984,6 @@
   [Document interface: document.implementation.createDocument(null, "", null) must inherit property "enableStyleSheetsForSet" with the proper type (33)]
     expected: FAIL
 
-  [Document interface: document.implementation.createDocument(null, "", null) must inherit property "referrer" with the proper type (36)]
-    expected: FAIL
-
   [Document interface: document.implementation.createDocument(null, "", null) must inherit property "dir" with the proper type (42)]
     expected: FAIL
 
@@ -7347,9 +7341,6 @@
   [Document interface: new Document() must have own property "location"]
     expected: FAIL
 
-  [Document interface: new Document() must inherit property "referrer" with the proper type (36)]
-    expected: FAIL
-
   [Document interface: new Document() must inherit property "dir" with the proper type (42)]
     expected: FAIL
 

tests/wpt/mozilla/tests/mozilla/referrer-policy/generic/referrer-policy-test-case.js

@@ -105,11 +105,10 @@ function ReferrerPolicyTestCase(scenario, testDescription, sanityChecker) {
 
         // Check the reported URL.
         test.step(function() {
-          // TODO - can uncomment when Document::Referrer is implemented
-          // assert_equals(result.referrer,
-          //               t._expectedReferrerUrl,
-          //               "Reported Referrer URL is '" +
-          //               t._scenario.referrer_url + "'.");
+          assert_equals(result.referrer,
+                        t._expectedReferrerUrl,
+                        "Reported Referrer URL is '" +
+                        t._scenario.referrer_url + "'.");
           assert_equals(result.headers.referer,
                         t._expectedReferrerUrl,
                         "Reported Referrer URL from HTTP header is '" +

tests/wpt/mozilla/tests/mozilla/referrer-policy/generic/template/document.html.template

@@ -16,7 +16,7 @@
              return(false);
       }
 
-      var referrer = 'referrer' in document ? document.referrer : undefined;
+      var referrer = document.referrer.length > 0 ? document.referrer : undefined;
 
       var result = {
         location: document.location.toString(),