Remove structured cloning restriction over accessor properties.

LayoutTests/fast/dom/Window/script-tests/postmessage-clone.js

 document.getElementById("description").innerHTML = "Tests that we clone object hierarchies";
 
 tryPostMessage('null');
 tryPostMessage('undefined');
 tryPostMessage('1');
 tryPostMessage('true');
 tryPostMessage('"1"');
 tryPostMessage('({})');
 tryPostMessage('({a:1})');
 tryPostMessage('({a:"a"})');
@@ skipping 136 matching lines @@
 tryPostMessage(thunk(
         'var obja = {get p() { return 42; }}; ' +
         'var msg = {a: obja, get b() { return obja; }}; ' +
         'return msg;'
     ), false, "evalThunk", function(v) {
         // Interestingly, the standard admits two answers here!
         doPassFail(v.a === v.b, "reference equality preserved (opposite order)");
         doPassFail((v.b.p === 42 && v.a.p === 42) ||
                    (v.b.p === null && v.a.p === null), "accessors used (opposite order)");
     });
-// We should nullify the results from accessors more than one level deep,
-// but leave other fields untouched.
+
+// Accessor properties (getters) are allowed on the cloned object,
+// with no side conditions on the values they might return. For a
+// short period, the spec mandated that accessor properties appearing
+// within the value of what an 'outermost' accessor property returned
+// should all map to null --
+// https://www.w3.org/Bugs/Public/show_bug.cgi?id=12101. This change
+// was reverted and accessor properties were allowed with no spec
+// restrictions on nesting.
+//
+// The tests below verify behavior surrounding such object structures,
+// but the coercions to null must no longer happen. We keep
+// the tests, as they usefully verify correctness in the handling of
+// accessor properties overall.

[Mike West, 2013/12/01 20:26:49]

I'd suggest just adding something like "Verify that accessors and non-accessors
are treated equivalently." as a comment in this file. The justification for that
change isn't really relevant to the test, and could be moved out to the commit
message.

[sof, 2013/12/01 21:35:11]

Done; indeed, information better kept with the commit message.

 tryPostMessage(thunk(
         'var obja = {get p() { return 42; }, q: 43}; ' +
         'return {get a() { return obja; }};'
     ), false, "evalThunk", function(v) {
-        doPassFail(v.a.p === null, "accessor value was nullified");
+        doPassFail(v.a.p === 42, "accessor value was not nullified");
         doPassFail(v.a.q === 43, "non-accessor value was not nullified");
     });
 tryPostMessage(thunk(
         'var objb = {get r() { return 44; }, t: 45}; ' +
         'var obja = {get p() { return 42; }, q: 43, s: objb}; ' +
         'return {get a() { return obja; }};'
     ), false, "evalThunk", function(v) {
-        doPassFail(v.a.p === null, "accessor value was nullified");
+        doPassFail(v.a.p === 42, "accessor value was not nullified");
         doPassFail(v.a.q === 43, "non-accessor value was not nullified");
         doPassFail(v.s !== null, "non-accessor value was not nullified");
-        doPassFail(v.a.s.r === null, "accessor value was nullified");
+        doPassFail(v.a.s.r === 44, "accessor value was not nullified");
         doPassFail(v.a.s.t === 45, "non-accessor value was not nullified");
     });
 tryPostMessage(thunk(
         'var objb = {get r() { return 44; }, t: 45}; ' +
         'var obja = {get p() { return 42; }, q: 43, s: [objb]}; ' +
         'return {get c() { return 47; }, get a() { return obja; }, get b() { return 46; } };'
     ), false, "evalThunk", function(v) {
         doPassFail(v.b === 46, "accessor value was not nullified");
         doPassFail(v.c === 47, "accessor value was not nullified");
-        doPassFail(v.a.p === null, "accessor value was nullified");
+        doPassFail(v.a.p === 42, "accessor value was not nullified");
         doPassFail(v.a.q === 43, "non-accessor value was not nullified");
         doPassFail(v.a.s !== null, "non-accessor value was not nullified");
         doPassFail(v.a.s !== undefined, "non-accessor value is defined");
         doPassFail(v.a.s[0] !== null, "non-accessor value was not nullified");
         doPassFail(v.a.s[0] !== undefined, "non-accessor value is defined");
-        doPassFail(v.a.s[0].r === null, "accessor value was nullified");
+        doPassFail(v.a.s[0].r === 44, "accessor value was not nullified");
         doPassFail(v.a.s[0].t === 45, "non-accessor value was not nullified");
     });
 
 // We need to pass out the exception raised from internal accessors.
 tryPostMessage(thunk(
         'return {get a() { throw "accessor-exn"; }};'
     ), true, null, 'accessor-exn');
-// We should still return the exception raised from nulled-out accessors.
 tryPostMessage(thunk(
         'var obja = {get p() { throw "accessor-exn"; }}; ' +
         'return {get a() { return obja; }};'
     ), true, null, 'accessor-exn');
-// We should run the first nullified accessor, but no more.
 tryPostMessage(thunk(
         'window.bcalled = undefined; ' +
         'window.acalled = undefined; ' +
         'window.pcalled = undefined; ' +
         'var objb = {get b() { window.bcalled = true; return 42; }}; ' +
         'var obja = {get a() { window.acalled = true; return objb; }}; ' +
         'return { get p() { window.pcalled = true; return obja; }};'
     ), false, "evalThunk", function(v) {
-        doPassFail(v.p.a === null, "accessor value was nullified");
+        doPassFail(v.p.a.b === 42, "accessor value was not nullified");
         doPassFail(window.pcalled === true, "window.pcalled === true");
         doPassFail(window.acalled === true, "window.acalled === true");
-        doPassFail(window.bcalled === undefined, "window.bcalled === undefined");
+        doPassFail(window.bcalled === true, "window.bcalled === true");
     });
 
 // Reference equality between Boolean objects must be maintained.
 tryPostMessage(thunk(
         'var t1 = new Boolean(true); ' +
         'var t2 = new Boolean(true); ' +
         'var f1 = new Boolean(false); ' +
         'var f2 = new Boolean(false); ' +
         'return [t1, t1, t2, f1, f1, f2];'
     ), false, "evalThunk", function(v) {
@@ skipping 99 matching lines @@
             doPassFail(v[0].length === window.fileList.length, "FileList length sent correctly");
             doPassFail(v[0][0] !== v[1], "FileList should not respect reference equality (0)");
             doPassFail(v[0][1] !== v[2], "FileList should not respect reference equality (1)");
             doPassFail(v[0][0].name == window.file0.name, "FileList preserves order and data (name0)");
             doPassFail(v[0][1].name == window.file1.name, "FileList preserves order and data (name1)");
             doPassFail(equal(v[0][0].lastModifiedDate, window.file0.lastModifiedDate), "FileList preserves order and data (date0)");
             doPassFail(equal(v[0][1].lastModifiedDate, window.file1.lastModifiedDate), "FileList preserves order and data (date1)");
         });
 }
 tryPostMessage('"done"');