Add additional usage metrics for DOMStringList methods

Source/core/dom/DOMStringList.idl

Index: Source/core/dom/DOMStringList.idl
diff --git a/Source/core/dom/DOMStringList.idl b/Source/core/dom/DOMStringList.idl
index 02926f66392101f9689489bc4c9c874cded62f27..3821bd83be36d7c9cc5509d53ca1d760da4a6201 100644
--- a/Source/core/dom/DOMStringList.idl
+++ b/Source/core/dom/DOMStringList.idl
@@ -30,6 +30,8 @@
     WillBeGarbageCollected,
 ] interface DOMStringList {
     readonly attribute unsigned long length;
-    [Measure] getter DOMString? item(unsigned long index);
-    [MeasureAs=DOMStringListContains] boolean contains(DOMString string);
+    getter DOMString? (unsigned long index);
+
+    [CallWith=ExecutionContext] DOMString? item(unsigned long index);
+    [CallWith=ExecutionContext,MeasureAs=DOMStringListContains] boolean contains(DOMString string);
 };