Store parser's current line when script elements are created.

Use the newly stored line as the starting line number when
evaluating JS. This ensures that inline scripts will report
errors with meaningful line numbers.

components/script/dom/servoparser/xml.rs

@@ -134,8 +134,9 @@ impl TreeSink for Sink {
             ns: name.namespace_url,
             local: name.local,
         };
+        //TODO: Add ability to track lines to API of xml5ever
         let elem = Element::create(name, prefix, &*self.document,
-                                   ElementCreator::ParserCreated);
+                                   ElementCreator::ParserCreated(1));
 
         for attr in attrs {
             let name = QualName {