Merge 174141 "HTML Imports: Take care of cycles according to the..."

Source/core/dom/custom/CustomElementMicrotaskImportStep.cpp

Index: Source/core/dom/custom/CustomElementMicrotaskImportStep.cpp
===================================================================
--- Source/core/dom/custom/CustomElementMicrotaskImportStep.cpp	(revision 174593)
+++ Source/core/dom/custom/CustomElementMicrotaskImportStep.cpp	(working copy)
@@ -55,6 +55,12 @@
 {
 }
 
+void CustomElementMicrotaskImportStep::parentWasChanged()
+{
+    m_queue = CustomElementMicrotaskQueue::create();
+    m_import.clear();
+}
+
 bool CustomElementMicrotaskImportStep::shouldWaitForImport() const
 {
     return m_import && !m_import->isLoaded();