servo: Merge #3791 - Really fix #3738 by only processing iframe src attributes during parsing (from jdm:moreiframe); r=Ms2ger

....

Source-Repo: https://github.com/servo/servo
Source-Revision: 39d5f09350e3ec251b9f16cb55a12febeeeda4f8

servo/components/script/dom/htmliframeelement.rs

@@ -121,7 +121,7 @@ impl<'a> HTMLIFrameElementHelpers for JSRef<'a, HTMLIFrameElement> {
         }));
 
         let doc = document_from_node(self).root();
-        if doc.ReadyState() != DocumentReadyStateValues::Complete {
+        if doc.ReadyState() == DocumentReadyStateValues::Loading {
             // https://github.com/servo/servo/issues/3738
             // We can't handle dynamic frame tree changes in the compositor right now.
             let ConstellationChan(ref chan) = page.constellation_chan;

servo/tests/html/test-iframe.html

@@ -0,0 +1,2 @@
+<iframe id="whee"></iframe>
+<script>document.getElementById('whee').src = "http://google.com"</script>