[ES6 modules] accessing document.currentScript on module scripts should not crash

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 9c73cbac6ab4afb45ac886dc77914bf1bbfdf3e8..fceb6652aed8561eb7a9b867e323fd0799e1c87a 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -5289,8 +5289,10 @@ KURL Document::OpenSearchDescriptionURL() {
 
 void Document::currentScriptForBinding(
     HTMLScriptElementOrSVGScriptElement& script_element) const {
-  if (!current_script_stack_.IsEmpty())
-    current_script_stack_.back()->SetScriptElementForBinding(script_element);
+  if (!current_script_stack_.IsEmpty()) {
+    if (ScriptElementBase* script_element_base = current_script_stack_.back())
+      script_element_base->SetScriptElementForBinding(script_element);
+  }
 }
 
 void Document::PushCurrentScript(ScriptElementBase* new_current_script) {