qmljs: correctly handle js string templates

In most cases we do want to visit the expressions in a function
template. Changing its accept0 would force those not wanting to visit
it to iterate on the templates (currently a linked list), so we add a
visit method explicitly visiting the expression in all the needed
places.

Fixes: QTCREATORBUG-21869
Change-Id: I47733544bfd32eec357810b97242608b8f7de572
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>

src/plugins/qmljstools/qmljssemanticinfo.cpp

@@ -127,6 +127,12 @@ protected:
         return handleLocationAst(ast);
     }
 
+    bool visit(AST::TemplateLiteral *ast) override
+    {
+        AST::Node::accept(ast->expression, this);
+        return true;
+    }
+
     void throwRecursionDepthError() override
     {
         qWarning("Warning: Hit maximum recursion depth when visiting the AST in AstPath");