LibCpp: Parse sizeof() expression

Author: https://github.com/itamar8910
Commit: fc503b1368
Pull-request: https://github.com/SerenityOS/serenity/pull/6009

Userland/Libraries/LibCpp/AST.cpp

@@ -530,4 +530,11 @@ void CppCastExpression::dump(size_t indent) const
         m_expression->dump(indent + 1);
 }
 
+void SizeofExpression::dump(size_t indent) const
+{
+    ASTNode::dump(indent);
+    if(m_type)
+        m_type->dump(indent+1);
+}
+
 }