Take throw-on-dynamic-markup-insertion-counter into account when check script safety.

components/script/dom/document.rs

@@ -1896,7 +1896,12 @@ impl Document {
 
     pub fn can_invoke_script(&self) -> bool {
         match self.get_current_parser() {
-            Some(parser) => parser.parser_is_not_active(),
+            Some(parser) => {
+                // It is safe to run script if the parser is not actively parsing,
+                // or if it is impossible to interact with the token stream.
+                parser.parser_is_not_active() ||
+                self.throw_on_dynamic_markup_insertion_counter.get() > 0
+            }
             None => true,
         }
     }

tests/wpt/metadata/custom-elements/microtasks-and-constructors.html.ini

@@ -1,3 +0,0 @@
-[microtasks-and-constructors.html]
-  expected: CRASH
-  bug: https://github.com/servo/servo/issues/19392

tests/wpt/metadata/custom-elements/parser/parser-fallsback-to-unknown-element.html.ini

@@ -1,3 +0,0 @@
-[parser-fallsback-to-unknown-element.html]
-  expected: CRASH
-  bug: https://github.com/servo/servo/issues/19392