mshtml: Ignore attempts to set read only builtin properties in IE9+ mode.

dlls/mshtml/dispex.c

@@ -1101,6 +1101,10 @@ static HRESULT builtin_propput(DispatchEx *This, func_info_t *func, DISPPARAMS *
     }
 
     if(!func->put_vtbl_off) {
+        if(dispex_compat_mode(This) >= COMPAT_MODE_IE9) {
+            WARN("No setter\n");
+            return S_OK;
+        }
         FIXME("No setter\n");
         return E_FAIL;
     }

dlls/mshtml/tests/es5.js

@@ -949,3 +949,8 @@ sync_test("preventExtensions", function() {
 
     ok(Object.preventExtensions.length === 1, "Object.preventExtensions.length = " + Object.preventExtensions.length);
 });
+
+sync_test("head_setter", function() {
+    document.head = "";
+    ok(typeof(document.head) === "object", "typeof(document.head) = " + typeof(document.head));
+});