Highlight the entire covering_element's text range

Instead of only highlighting the requested text_range we want to
highlight the text range of the covering element which might be greater
than the given text range. This is to prevent us from breaking the
assumption that the highlighted elements in a node are always contained
inside the root text range.

crates/ide/src/syntax_highlighting.rs

@@ -66,6 +66,7 @@ pub(crate) fn highlight(
                     NodeOrToken::Node(it) => it,
                     NodeOrToken::Token(it) => it.parent(),
                 };
+                let range = node.text_range();
                 (node, range)
             }
             None => (source_file.syntax().clone(), source_file.syntax().text_range()),