Return MaybeHandle from SetElement and DeleteElement.

src/liveedit.cc

Index: src/liveedit.cc
diff --git a/src/liveedit.cc b/src/liveedit.cc
index f70394dbc926e65491745a1895c14cee7ea20d59..ee22f8901dd0d08ffb164e04b7881b1dc30b6d1a 100644
--- a/src/liveedit.cc
+++ b/src/liveedit.cc
@@ -55,10 +55,7 @@ void SetElementSloppy(Handle<JSObject> object,
   // Ignore return value from SetElement. It can only be a failure if there
   // are element setters causing exceptions and the debugger context has none
   // of these.
-  Handle<Object> no_failure =
-      JSObject::SetElement(object, index, value, NONE, SLOPPY);
-  ASSERT(!no_failure.is_null());
-  USE(no_failure);
+  JSObject::SetElement(object, index, value, NONE, SLOPPY).Assert();
 }